Bank Officer Interview Question and Answers
1. What is Balance of Trade?
The value of a country’s exports minus the value of its imports. Unless specified as the balance of merchandise trade, it normally incorporates trade in services, including earnings (interest, dividends, etc.) on financial assets.
2. What is Balanced Trade?
When A balance of trade equal to zero. (exports-imports=0)
3. What is Balance of merchandise trade?
The value of a country’s merchandise exports minus the value of its merchandise imports.
4. What is a favorable balance of trade?
It is the difference between exports and imports. Debit items include imports, foreign aid, domestic spending abroad and domestic investments abroad. Credit items include exports, foreign spending in the domestic economy and foreign investments in the domestic economy. A country has a trade deficit if it imports more than it exports; the opposite scenario is a trade surplus.
5. What is Balance of Payments?
A list, or accounting, of all of a country’s international transactions for a given time period, usually one year. Payments into the country (receipts) are entered as positive numbers, called credits; payments out of the country (payments) are entered as negative numbers called debits. A single number summarizing all of a country’s international transactions: the balance of payments surplus.
6. What is Balance of payments adjustment mechanism?
Any process, especially any automatic one, by which a country with a payments imbalance moves toward balance of payments equilibrium
7. What is Monopolistic Competition?
A market structure in which there are many sellers each producing a differentiated product. Each can set its own price and quantity, but is too small for that to matter for prices and quantities of other producers in the industry.
8. What is MFN?
MFN stands for Most Favoured Nation. The principle, fundamental to the GATT, of treating imports from a country on the same basis as that given to the most favored other nation. That is, and with some exceptions, every country gets the lowest tariff that any country gets, and reductions in tariffs to one country are provided also to others.
9. What is Gold Standard?
A monetary system in which both the value of a unit of the currency and the quantity of it in circulation are specified in terms of gold. If two currencies are both on the gold standard, then the exchange rate between them is approximately determined by their two prices in terms of gold.
10. What is Balance on capital account?
A country’s receipts minus payments for capital account transactions.
11. What is Balance on current account ?
A country’s receipts minus payments for current account transactions. Equals the balance of trade plus net inflows of transfer payments.
12. What is a Balanced budget ?
A government budget surplus that is zero, thus with net tax revenue equaling expenditure. A balanced budget change in policy or behavior is one in which a component of the government budget, usually taxes, is adjusted as necessary to maintain a balanced budget.
13. What is balanced growth of an Economy?
Growth of an economy in which all aspects of it, especially factors of production, grow at the same rate.
14. What is a Bank rate
The interest rate charged by a central bank to commercial banks for very short term loans.
15. What is a Repo?
Repo is “Repurchase Agreement. An agreement to sell a security for a specified price and to buy it back later at another specified price. A repo is essentially a secured loan.
16. What is Repo Rate?
Whenever the banks have any shortage of funds they can borrow it from RBI. Repo rate is the rate at which our banks borrow rupees from RBI. A reduction in the repo rate will help banks to get money at a cheaper rate. When the repo rate increases borrowing from RBI becomes more expensive. On March 4, 2009 it was 5% in India (please check the latest figure by RBI)
17. What is CRR Rate in India?
Cash reserve Ratio (CRR) is the amount of funds that the banks have to keep with RBI. If RBI decides to increase the percent of this, the available amount with the banks comes down. RBI is using this method (increase of CRR rate), to drain out the excessive money from the banks.
18. What is a Reverse Repo Rate?
Reverse Repo rate is the rate at which Reserve Bank of India (RBI) borrows money from banks. Banks are always happy to lend money to RBI since their money are in safe hands with a good interest. An increase in Reverse repo rate can cause the banks to transfer more funds to RBI due to this attractive interest rates. It can cause the money to be drawn out of the banking system. Due to this fine tuning of RBI using its tools of CRR, Bank Rate, Repo Rate and Reverse Repo rate our banks adjust their lending or investment rates for common man. On March 4, 2009 Reverse Repo Rate is 3.5% (please check latest rate by RBI)
19. What is SLR Rate?
SLR (Statutory Liquidity Ratio) is the amount a commercial bank needs to maintain in the form of cash, or gold or govt. approved securities (Bonds) before providing credit to its customers. SLR rate is determined and maintained by the RBI (Reserve Bank of India) in order to control the expansion of bank credit.
20. How is SLR determined?
SLR is determined as the percentage of total demand and percentage of time liabilities. Time Liabilities are the liabilities a commercial bank liable to pay to the customers on their anytime demand. .
21. What is the Need of SLR?
With the SLR (Statutory Liquidity Ratio), the RBI can ensure the solvency a commercial bank. It is also helpful to control the expansion of Bank Credits. By changing the SLR rates, RBI can increase or decrease bank credit expansion. Also through SLR, RBI compels the commercial banks to invest in government securities like government bonds..
22. What is the main use of SLR?
SLR is used to control inflation and propel growth. Through SLR rate tuning the money supply in the system can be controlled efficiently.
23. What is Inflation in India?
Increase in the overall price level of an economy, usually as measured by the CPI /WPI or by the implicit price deflator. Inflation is as an increase in the price of bunch of Goods and services that projects the Indian economy. An increase in inflation figures occurs when there is an increase in the average level of prices in Goods and services. Inflation happens when there are less Goods and more buyers, this will result in increase in the price of Goods, since there is more demand and less supply of the goods..
24. What is Deflation?
A fall in the general level of prices. Unlikely unless the rate of inflation is already low, it may then be due either to a surge in productivity or, less favorably, to a recession. Deflation is the continuous decrease in prices of goods and services. Deflation occurs when the inflation rate becomes negative (below zero) and stays there for a longer period.
25. What is a Barter economy?
An economic model of international trade in which goods are exchanged for goods without the existence of money. Most theoretical trade models take this form in order to abstract from macroeconomic and monetary considerations.
26.What is Basel I?
Also known at Basel Capital Accord, this was an agreement in 1988 by the Basel Committee of central bankers to measure the credit risk of commercial banks and set minimum standards for bank capital in order to reduce the likelihood of international repercussions due to bank failures.
27.What is Basel II?
The Basel II Framework describes a more comprehensive measure and minimum standard for capital adequacy that national supervisory authorities are now working to implement through domestic rule-making and adoption procedures. It seeks to improve on the existing rules by aligning regulatory capital requirements more closely to the underlying risks that banks face. In addition, the Basel II Framework is intended to promote a more forward-looking approach to capital supervision, one that encourages banks to identify the risks they may face, today and in the future, and to develop or improve their ability to manage those risks. As a result, it is intended to be more flexible and better able to evolve with advances in markets and risk management practices.
The efforts of the Basel Committee on Banking Supervision to revise the standards governing the capital adequacy of internationally active banks achieved a critical milestone in the publication of an agreed text in June 2004.
28.What is a Beggar thy neighbor policy?
For a country to use a policy for its own benefit that harms other countries. Examples are optimal tariffs and, in a recession, tariffs and/or devaluation to create employment.
29. What is a Bill of Lading?
This term is normally used in shipping industry. The receipt given by a transportation company to an exporter when the former accepts goods for transport. It includes the contract specifying what transport service will be provided and the limits of liability.
30. What is the use of color boxes in WTO category of subsidies?
Used with a color, a category of subsidies based on status in WTO: red=forbidden, amber or orange=go slow, green=permitted, blue=subsidies tied to production limits. Terminology seems only to be used in agriculture, where in fact there is no red box.
31. What is a fiscal deficit?
A deficit in the government budget of a country and represents the excess of expenditure over income. So this is the amount of borrowed funds required by the government to meet its expenditures completely.
India’s fiscal deficit widened to Rs. 541.58 billion in April, 2009 as compared to Rs. 329.39 billion rupees in April 2008.
32. What is Black Money ?
Black Money is the unaccounted money concealed from the tax authorities. The black money runs a parallel economy adversely affecting the distribution of wealth & income in the economy.
The total amount of black money globally is estimated between $2.1 and 2.5 trillion. This is roughly about seven percent of the world’s GDP.
33.What is a Black Market?
A black market is an illegal market, in which something is bought and sold outside of official government-sanctioned channels. Black markets tend to arise when a government tries to fix a price without itself providing all of the necessary supply or demand. Black markets in foreign exchange almost always exist when there are exchange controls.
34.What is a blue chip company? Why it is blue color only used in such companies?
A blue chip is concerned with stocks & shares of company, which are well established and whose purchase is considered extremely safe. Due to stable earnings and no extensive liabilities these companies are called blue chip companies.
The term blue chip comes from casinos, where blue chips stand for counters of the highest value. Most blue chip stocks pay regular dividends, even when business is faring worse than usual.
35.What is a direct Tax?
A direct tax is that which is paid directly by someone to taxing authority. Income tax and property tax are examples of direct tax. They are not shifted to somebody else.
36.What is an Indirect Tax?
This type of tax is not paid by someone directly to the authorities and it is actually passed on to the other in the form of increased cost. They are levied on goods and services produced or purchased. Excise tax, Sales tax, VAT are indirect taxes.
37.What are LDCs or Least Developed Countries?
Least Developed Countries (LDCs) are countries which as per United Nations show the lowest indicators of socioeconomic development.
They have lowest Human Development Index ratings of all countries in the world.
A country which has three-year average Gross national Income per capita of less than US $750 is tagged as LDC. a LDC must have an income of $ 900 to escape this tag. Besides if thse countries show human resource weakness based on indicators of nutrition, health, education and adult literacy and also or economic vulnerability based on instability of economy . Currently UN has tagged 49 countries in LDC. India is not an LDC.
38.What are Middle Income Countries ?
Middle-income countries (MICs) are the 86 countries that fall into the middle-income range set by the Bank’s World Development Indicators. They account for just under half of the world’s population; are home to one-third of people across the globe living on less than $2 per day; and are found in all six of the Bank’s geographical regions. They cover a wide income range, with the highest income MIC having a per capita income 10 times that of the lowest.
39.What is Policy of Laissez Faire?
Laissez Faire is a French term and means no interference. It is a doctrine that states that government generally should not intervene in the marketplace.
40.What is the difference between Monopoly and Monopsony ?
In monopsony only one buyer faces many sellers. So this is called Buyer’s Monopoly. It is a rare situation in today’s economy.
In monopoly one seller faces many buyers. As the only purchaser of a good or service, the “monopsonist” may dictate terms to its suppliers in the same manner that a monopolist controls the market for its buyers.
41.What is the main function of Competition Commission of India?
CCI is an independent body which become operational w.e.f. May 20, 2009 and is responsible for investigating the mergers, market shares & conditions besides regulating firms. CCI will ultimately replace the Monopolies and Restrictive Trade Practices Commission (MRTPC) ofIndia.
42.What is Lead Bank Scheme?
Lead bank scheme was introduced around 40 years ago and recently it was in the news as a high level committee chaired by RBI Deputy Governor Usha Thorat was constituted to review and revitalize this scheme. The scheme aims at facilitating credit delivery to the farfetched areas ofIndia. There are members of the committee from NABARD and SIDBI. Thus the scheme focuses upon financial inclusion.
The Opinion of this committee is that full financial inclusion is possible only if it makes a facility of opening of no frill accounts backed by other specialized services.
43.What are Nostro & Vostro Accounts ?
A nostro account is maintained by an Indian Bank in the foreign countries for a facility of easy clearing of their transactions. For instance, if the bank pays a demand drawn on it by its correspondent bank, there is no delay because the foreign corresponded bank would already have credited the nostro account of the paying bank while issuing the demand draft.
A vostro account is maintained by a foreign bank in India with their corresponding bank.
44.From which country India imports maximum?
From China. Import from China was $ 24.16 billion in 2008-09, which got doubled in 3 years. This is 10.3 % of all the imports of India.
45.What is Gold Standard?
A system of setting currency values whereby the participating countries commit to fix the prices of their domestic currencies in terms of a specified amount of gold.
46.What is a Free Float Exchange Rate system?
An exchange rate system characterized by the absence of government intervention. Also known as a clean float.
47.What are Special Drawing rights SDR?
SDR are new form of international reserve assets, created by the International Monetary Funds in 1967. The value of SDR is based on a portfolio of widely used currencies and they are maintained as accounting entries and not as hard currency or physical assets like Gold.
48.What are the requirements to open a New Branch in Rural Area?
Since 2006, RBI has approved the opening of new branches only on the condition that at least half of such branches are opened in under-banked areas as notified by the regulator.
The opening of branches by banks is governed by the provisions of Section 23 of the Banking Regulation Act, 1949. In terms of these provisions, banks cannot open a new place of business inIndia or abroad or change otherwise than within the same city, town or village, the location of the existing place of business without the prior approval of the ReserveBank of India (RBI). Thus, it is mandatory for RRBs to seek prior approval/ license from Rural Planning and Credit Department (RPCD) of RBI before opening of new branches/offices.
RRB should fulfill the following conditions to become eligible for opening of new branch/es.
1. It should not have defaulted in maintenance of SLR and CRR during the last two years.
2. The RRB should be making operational profits, its net worth should show improvement 3. Its net NPA ratio should not exceed 8 per cent.
49.What is concept sustainable Development?
Meeting the needs of the present without compromising the ability of future generations to meet their needs is called sustainable development. This concept is popular in present context of development.
50.What is the meaning of Financial Inclusion?
Today is is well recognized that large population of India is out of reach of the formal banking services. Financial inclusion is the concept which has been floated to bring the most of the rural population / area under the net of the financial and banking services.
51. What is SATMO?
SATMO is Satellite Money Order Service introduced by Postal Department Govt. of India on December 16, 1994. However this scheme could not make its headway due to functional complicacies.
52. What is “Vande Mataram Scheme” ?
Vande mataram schem is a nationwide programme aimed at improving ante and post-natal care–which was launched on February 9, 2004. The scheme envisages free ante and post-natal check-ups, tips to avoid nutritional problems and anemia and counseling on small family norm and is a major initiative in Public Private partnerships during emergency.
53. What is Golden Handshake Scheme?
Golden handshake scheme is a Govt. of India scheme introduced as a Voluntary retirement Scheme (VRS) in Industrial Policy Resolution 1991 for reducing the pressure of extra employees on public sector enterprises.
54. What is India Brand Equity Fund?
This is a scheme to promote Indian Brands in Overseas Markets with the primary objective of brand promotion and not export promotion. To make the “Made in India” label a symbol of quality, competitive price, reliability and service to the customer & to project India as a reliable supplier of quality goods and services. It was established on July 11, 1996.
55. What is Jago Grahak Jago”?
The Consumer Awareness Scheme for the XI Plan amounting to a total of Rs. 409 crores has been approved by the Cabinet Committee on Economic Affairs on 24.01.08. This scheme has been formulated to give an increased thrust to a multi media publicity campaign to make consumers aware of their rights. The slogan ‘Jago Grahak Jago’ is part of the publicity campaign undertaken in the last few years.
‘Jago Grahak Jago’ has become the focal theme through which issues concerning the functioning of almost all Government Departments having a consumer interface can been addressed. To achieve this objective joint campaigns have been undertaken/are being undertaken with a number of Government Departments.
56. What is a revolving credit?
Revolving credit is a type of credit that does not have a fixed number of payments. Corporate revolving credit facilities are typically used to provide liquidity for a company’s day-to-day operations.The credit cards are examples of revolving credit. They are renewed automatically until the notice of cancellation is receieved. The time of repayment is specified.
57. What is Gender Budgeting?
Gender budgeting is the process of conceiving, planning, approving, executing, monitoring, analyzing and auditing budgets in a gender-sensitive way. Gender Budgeting is actually an attempt to women upliftment without any sex discrimination while formulating the policies and making allocation for them.
Gender Budgeting is a process that entails incorporating a gender perspective at various stages- planning/ policy/ programme formulation, assessment of needs of target groups, allocation of resources, implementation, impact assessment, reprioritization of resources.
Gender Responsive Budget and Gender Mainstreaming are outcomes of Gender Budgeting.
58. What is Soft Currency?
Soft currency is opposite of hard currency and it indicates a type of currency whose value may depreciate rapidly or that is difficult to convert into other currencies. Soft currency can be in the form of paper, electronic or debt-based “IOUs” which have in the past been used in place of hard currency. This currency has limited convertibility into gold and other currencies.
59. What are factors of production?
The resources and the inputs which are required to produce a good or service is called factor of production. The basic categories are land labor and capital.
60. What is the principle of Diminishing returns?
This principle says that if one factor of production is fixed and constant additions of other factors are combined with this, the marginal productivity of variable factors will eventually decline. According to this relationship, in a production system with fixed and variable inputs (say factory size and labor), beyond some point, each additional unit of the variable input yields smaller and smaller increases in output. Conversely, producing one more unit of output costs more and more in variable inputs.
Core Java Interview Questions and Answers
Core Java Interview Questions and Answers
1. What is the difference between an Interface and an Abstract class?
An Abstract class declares have at least one instance method that is declared abstract which will be implemented by the subclasses. An abstract class can have instance methods that implement a default behavior. An Interface can only declare constants and instance methods, but cannot implement default behavior.
2. What is the purpose of garbage collection in Java, and when is it used?
The purpose of garbage collection is to identify and discard objects that are no longer needed by a program so that their resources can be reclaimed and reused. A Java object is subject to garbage collection when it becomes unreachable to the program in which it is used.
3. Describe synchronization in respect to multithreading.?
With respect to multithreading, synchronization is the capability to control the access of multiple threads to shared resources. Without synchonization, it is possible for one thread to modify a shared variable while another thread is in the process of using or updating same shared variable. This usually leads to significant errors.
4. Explain different way of using thread?
The thread could be implemented by using runnable interface or by inheriting from the Thread class. The former is more advantageous, ’cause when you are going for multiple inheritance..the only interface can help.
5. What are pass by reference and passby value?
Pass By Reference means the passing the address itself rather than passing the value. Passby Value means passing a copy of the value to be passed.
6. What is HashMap and Map?
Map is Interface and Hashmap is class that implements that.
7. Difference between HashMap and HashTable?
The HashMap class is roughly equivalent to Hashtable, except that it is unsynchronized and permits nulls. (HashMap allows null values as key and value whereas Hashtable doesnt allow). HashMap does not guarantee that the order of the map will remain constant over time. HashMap is non synchronized and Hashtable is synchronized.
8. Difference between Vector and ArrayList?
Vector is synchronized whereas arraylist is not.
9. Difference between Swing and Awt?
AWT are heavy-weight componenets. Swings are light-weight components. Hence swing works faster than AWT.
10. What is the difference between a constructor and a method?
A constructor is a member function of a class that is used to create objects of that class. It has the same name as the class itself, has no return type, and is invoked using the new operator. A method is an ordinary member function of a class. It has its own name, a return type (which may be void), and is invoked using the dot operator.
11. What is an Iterators?
Some of the collection classes provide traversal of their contents via a java.util.Iterator interface. This interface allows you to walk a collection of objects, operating on each object in turn. Remember when using Iterators that they contain a snapshot of the collection at the time the Iterator was obtained; generally it is not advisable to modify the collection itself while traversing an Iterator.
12. State the significance of public, private, protected, default modifiers both singly and in combination and state the effect of package relationships on declared items qualified by these modifiers.?
Public : Public class is visible in other packages, field is visible everywhere (class must be public too) private : Private variables or methods may be used only by an instance of the same class that declares the variable or method, A private feature may only be accessed by the class that owns the feature. protected : Is available to all classes in the same package and also available to all subclasses of the class that owns the protected feature.This access is provided even to subclasses that reside in a different package from the class that owns the protected feature. default :What you get by default ie, without any access modifier (ie, public private or protected).It means that it is visible to all within a particular package.
13. What is an abstract class?
Abstract class must be extended/subclassed (to be useful). It serves as a template. A class that is abstract may not be instantiated (ie, you may not call its constructor), abstract class may contain static data. Any class with an abstract method is automatically abstract itself, and must be declared as such. A class may be declared abstract even if it has no abstract methods. This prevents it from being instantiated.
14. What is static in java?
Static means one per class, not one for each object no matter how many instance of a class might exist. This means that you can use them without creating an instance of a class.Static methods are implicitly final, because overriding is done based on the type of the object, and static methods are attached to a class, not an object. A static method in a superclass can be shadowed by another static method in a subclass, as long as the original method was not declared final. However, you can’t override a static method with a nonstatic method. In other words, you can’t change a static method into an instance method in a subclass.
1. What is the difference between an Interface and an Abstract class?
An Abstract class declares have at least one instance method that is declared abstract which will be implemented by the subclasses. An abstract class can have instance methods that implement a default behavior. An Interface can only declare constants and instance methods, but cannot implement default behavior.
2. What is the purpose of garbage collection in Java, and when is it used?
The purpose of garbage collection is to identify and discard objects that are no longer needed by a program so that their resources can be reclaimed and reused. A Java object is subject to garbage collection when it becomes unreachable to the program in which it is used.
3. Describe synchronization in respect to multithreading.?
With respect to multithreading, synchronization is the capability to control the access of multiple threads to shared resources. Without synchonization, it is possible for one thread to modify a shared variable while another thread is in the process of using or updating same shared variable. This usually leads to significant errors.
4. Explain different way of using thread?
The thread could be implemented by using runnable interface or by inheriting from the Thread class. The former is more advantageous, ’cause when you are going for multiple inheritance..the only interface can help.
5. What are pass by reference and passby value?
Pass By Reference means the passing the address itself rather than passing the value. Passby Value means passing a copy of the value to be passed.
6. What is HashMap and Map?
Map is Interface and Hashmap is class that implements that.
7. Difference between HashMap and HashTable?
The HashMap class is roughly equivalent to Hashtable, except that it is unsynchronized and permits nulls. (HashMap allows null values as key and value whereas Hashtable doesnt allow). HashMap does not guarantee that the order of the map will remain constant over time. HashMap is non synchronized and Hashtable is synchronized.
8. Difference between Vector and ArrayList?
Vector is synchronized whereas arraylist is not.
9. Difference between Swing and Awt?
AWT are heavy-weight componenets. Swings are light-weight components. Hence swing works faster than AWT.
10. What is the difference between a constructor and a method?
A constructor is a member function of a class that is used to create objects of that class. It has the same name as the class itself, has no return type, and is invoked using the new operator. A method is an ordinary member function of a class. It has its own name, a return type (which may be void), and is invoked using the dot operator.
11. What is an Iterators?
Some of the collection classes provide traversal of their contents via a java.util.Iterator interface. This interface allows you to walk a collection of objects, operating on each object in turn. Remember when using Iterators that they contain a snapshot of the collection at the time the Iterator was obtained; generally it is not advisable to modify the collection itself while traversing an Iterator.
12. State the significance of public, private, protected, default modifiers both singly and in combination and state the effect of package relationships on declared items qualified by these modifiers.?
Public : Public class is visible in other packages, field is visible everywhere (class must be public too) private : Private variables or methods may be used only by an instance of the same class that declares the variable or method, A private feature may only be accessed by the class that owns the feature. protected : Is available to all classes in the same package and also available to all subclasses of the class that owns the protected feature.This access is provided even to subclasses that reside in a different package from the class that owns the protected feature. default :What you get by default ie, without any access modifier (ie, public private or protected).It means that it is visible to all within a particular package.
13. What is an abstract class?
Abstract class must be extended/subclassed (to be useful). It serves as a template. A class that is abstract may not be instantiated (ie, you may not call its constructor), abstract class may contain static data. Any class with an abstract method is automatically abstract itself, and must be declared as such. A class may be declared abstract even if it has no abstract methods. This prevents it from being instantiated.
14. What is static in java?
Static means one per class, not one for each object no matter how many instance of a class might exist. This means that you can use them without creating an instance of a class.Static methods are implicitly final, because overriding is done based on the type of the object, and static methods are attached to a class, not an object. A static method in a superclass can be shadowed by another static method in a subclass, as long as the original method was not declared final. However, you can’t override a static method with a nonstatic method. In other words, you can’t change a static method into an instance method in a subclass.
OOPs Java Basic Interview Questions and answers
OOPs Java Basic Interview Questions and answers
1. What is a virtual function in C++?
Simply put, the virtual keyword enables a function to be ‘virtual’ which then gives possibility for that function to be overridden (redefined) in one or more descendant classes. It is a good feature since the specific function to call is determined at run-time. In other words, a virtual function allows derived classes to replace the implementation provided by the base class.
2. What is the difference between private, protected, and public?
These keywords are for allowing privilages to components such as functions and variables.
Public: accessible to all classes
Private: accessible only to the class to which they belong
Protected: accessible to the class to which they belong and any subclasses.
3. What is a cartesian product in PL/SQL?
When a Join condition is not specified by the programmer or is invalid(fails), PL/SQL forms a Cartesian product.
In a Cartesian product, all combinations of rows will be displayed.
For example, All rows in the first table are joined to all rows in the second table. It joins a bunch of rows and it’s result is rarely useful unless you have a need to combine all rows from all tables.
4. What is mutual exclusion? How can you take care of mutual exclusion using Java threads?
Mutual exclusion is where no two processes can access critical regions of memory at the same time.
Java provides many utilities to deal with mutual exclusion with the use of threaded programming.
For mutual exclusion, you can simply use the synchronized keyword and explicitly or implicitly provide an Object, any Object, to synchronize on.
The runtime system/Java compiler takes care of the gruesome details for you. The synchronized keyword can be applied to a class, to a method, or to a block of code. There are several methods in Java used for communicating mutually exclusive threads such as wait( ), notify( ), or notifyAll( ). For example, the notifyAll( ) method wakes up all threads that are in the wait list of an object.
5. What are some advantages and disadvantages of Java Sockets?
Some advantages of Java Sockets:
* Sockets are flexible and sufficient. Efficient socket based programming can be easily implemented for general communications.
* Sockets cause low network traffic. Unlike HTML forms and CGI scripts that generate and transfer whole web pages for each new request, Java applets can send only necessary updated information.
Some disadvantages of Java Sockets:
* Security restrictions are sometimes overbearing because a Java applet running in a Web browser is only able to establish connections to the machine where it came from, and to nowhere else on the network
* Despite all of the useful and helpful Java features, Socket based communications allows only to send packets of raw data between applications. Both the client-side and server-side have to provide mechanisms to make the data useful in any way.
* Since the data formats and protocols remain application specific, the re-use of socket based implementations is limited.
1. What is a virtual function in C++?
Simply put, the virtual keyword enables a function to be ‘virtual’ which then gives possibility for that function to be overridden (redefined) in one or more descendant classes. It is a good feature since the specific function to call is determined at run-time. In other words, a virtual function allows derived classes to replace the implementation provided by the base class.
2. What is the difference between private, protected, and public?
These keywords are for allowing privilages to components such as functions and variables.
Public: accessible to all classes
Private: accessible only to the class to which they belong
Protected: accessible to the class to which they belong and any subclasses.
3. What is a cartesian product in PL/SQL?
When a Join condition is not specified by the programmer or is invalid(fails), PL/SQL forms a Cartesian product.
In a Cartesian product, all combinations of rows will be displayed.
For example, All rows in the first table are joined to all rows in the second table. It joins a bunch of rows and it’s result is rarely useful unless you have a need to combine all rows from all tables.
4. What is mutual exclusion? How can you take care of mutual exclusion using Java threads?
Mutual exclusion is where no two processes can access critical regions of memory at the same time.
Java provides many utilities to deal with mutual exclusion with the use of threaded programming.
For mutual exclusion, you can simply use the synchronized keyword and explicitly or implicitly provide an Object, any Object, to synchronize on.
The runtime system/Java compiler takes care of the gruesome details for you. The synchronized keyword can be applied to a class, to a method, or to a block of code. There are several methods in Java used for communicating mutually exclusive threads such as wait( ), notify( ), or notifyAll( ). For example, the notifyAll( ) method wakes up all threads that are in the wait list of an object.
5. What are some advantages and disadvantages of Java Sockets?
Some advantages of Java Sockets:
* Sockets are flexible and sufficient. Efficient socket based programming can be easily implemented for general communications.
* Sockets cause low network traffic. Unlike HTML forms and CGI scripts that generate and transfer whole web pages for each new request, Java applets can send only necessary updated information.
Some disadvantages of Java Sockets:
* Security restrictions are sometimes overbearing because a Java applet running in a Web browser is only able to establish connections to the machine where it came from, and to nowhere else on the network
* Despite all of the useful and helpful Java features, Socket based communications allows only to send packets of raw data between applications. Both the client-side and server-side have to provide mechanisms to make the data useful in any way.
* Since the data formats and protocols remain application specific, the re-use of socket based implementations is limited.
Motorola Interview Questions
Motorola Interview Questions
1. What is deadlock? How do you avoid it?
2. What is a Real Time OS.
3. Difference between Macro and ordinary definition.
4. What is the difference between widget & gadget in XWindows?
5. Write a C code to reverse a string using a recursive function, without swapping or using an extra memory.
6. What is a semaphore?
7. Difference between Class and Struct
8. What exactly happens after each system call in sockets, both at the client and at the server.
9. Describe VRTX
10. How does the scheduler know the time how it should be scheduled.
11. There are 1800 coins.one coin is counterfiet coin.how many minimum weight is required to find counterfiet coin.
12. Complete the series - 1 , 2 , 3 , 5 , 8 , ___
13. Explain strtok & strstr functions
14. Explain Breadth search and Depth search in binary tree.
1. What is deadlock? How do you avoid it?
2. What is a Real Time OS.
3. Difference between Macro and ordinary definition.
4. What is the difference between widget & gadget in XWindows?
5. Write a C code to reverse a string using a recursive function, without swapping or using an extra memory.
6. What is a semaphore?
7. Difference between Class and Struct
8. What exactly happens after each system call in sockets, both at the client and at the server.
9. Describe VRTX
10. How does the scheduler know the time how it should be scheduled.
11. There are 1800 coins.one coin is counterfiet coin.how many minimum weight is required to find counterfiet coin.
12. Complete the series - 1 , 2 , 3 , 5 , 8 , ___
13. Explain strtok & strstr functions
14. Explain Breadth search and Depth search in binary tree.
CICS Mainframes Interview Questions and Answers
CICS Mainframes Interview Questions and Answers
1. What is the meaning for CICS?
Customer Information Control System.
2. What do we do by using CICS?
CICS is normally used for Real-time or Online processing when that particular processing cannot wait for batch processing normally done at the end of the day for most installations.
3. What are the eight steps for a CICS program development?
Get the complete specification
Get related sourcebooks and subprograms
Design the program
Update the CICS Tables
Code and compile the map definition
Code the program
Compile the program
Test the program.
4. In a CICS development, do you compile the map or program first?
The map needs to be compiled first.
5. What is a transaction id or code?
A transaction is mostly a four letter unique predefined unit of work, a terminal work will use to invoke a specific map and the associated program.
6. What is a PCT and how it is used?
A PCT is a short name for Program Control Table, which contains the trans-id and the associated program which will be invoked when the trans-id is used.
7. What is a PPT and how it is used?
A PPT contains a valid list of program names and it also indicates the storage address if the program has already been loaded. CICS uses PPT to determine whether it will load a new copy of the program if the program is invoked.
8. Have you ever heard of SNT in CICS Processing?
Yes, it contains the names of all valid users of the system.
9. What is the use of DFHCOMMAREA and where it is located?
It helps to transfer data between two transactions and it is located in the LINKAGE SECTION.
10. Are you familiar with CEMT and CSMT functions? What does these transactions do for you?
These are normally supervisory functions, where they can be used to cancel tasks running at a different terminals. CSMT is used to update PPT. But I never had much chance to use them.
11. What transaction will you use to debug a CICS Program?
CEDF, which means CICS Execution Diagnostic facility.
12. What XCTL and LINK command is used for?
XCTL command transfers control to another program without setting up a return mechanism whereas the LINK command transfers control to next logical lower level with a return mechanism
13. Why the EXEC CICS HANDLE command is used?
It is used to specify what action the program needs to take when certain exceptional conditions occur.
14. Why the EXEC CICS RETURN command is used?
It is used simply to return control to CICS with no option and the terminal session ends.
15. What are the parameters will you use to code a SEND MAP command?
SEND MAP(name of the map)
MAPSET(name of the mapset which contains the specific map)
FROM(specifies the symbolic map)
MAPONLY(specifies dataonly needs to be sent)
DATAONLY(specifies that only data from the symbolic map needs to be sent)
ERASE/ERASEUP
CURSOR
16. How do you terminate each CICS commands?
EXEC CICS
intermediate commands
END-EXEC.
17. How do you obtain the storage dump from CICS?
CICS automatically adds the storage dump to a special file called dump data set. When the CICS is terminated, the dumps are automatically printed. The DSN can be found from the respective installation personnel.
18. What is the meaning for AEI9 CICS abend?
MAPFAIL.
19. What are the following entities represent?
EIBAID It is an one character field that indicates which attention key was used for the last RECEIVE command.
EIBTRMID This field supplies the name of the terminal running the task.
EIBCALEN This field represents the length of the communication area passed to my program. If no commarea is passed, it is set to zero.
20. How do you logoff from a CICS transaction?
Blank the screen, then type CSSF LOGOFF.
1. What is the meaning for CICS?
Customer Information Control System.
2. What do we do by using CICS?
CICS is normally used for Real-time or Online processing when that particular processing cannot wait for batch processing normally done at the end of the day for most installations.
3. What are the eight steps for a CICS program development?
Get the complete specification
Get related sourcebooks and subprograms
Design the program
Update the CICS Tables
Code and compile the map definition
Code the program
Compile the program
Test the program.
4. In a CICS development, do you compile the map or program first?
The map needs to be compiled first.
5. What is a transaction id or code?
A transaction is mostly a four letter unique predefined unit of work, a terminal work will use to invoke a specific map and the associated program.
6. What is a PCT and how it is used?
A PCT is a short name for Program Control Table, which contains the trans-id and the associated program which will be invoked when the trans-id is used.
7. What is a PPT and how it is used?
A PPT contains a valid list of program names and it also indicates the storage address if the program has already been loaded. CICS uses PPT to determine whether it will load a new copy of the program if the program is invoked.
8. Have you ever heard of SNT in CICS Processing?
Yes, it contains the names of all valid users of the system.
9. What is the use of DFHCOMMAREA and where it is located?
It helps to transfer data between two transactions and it is located in the LINKAGE SECTION.
10. Are you familiar with CEMT and CSMT functions? What does these transactions do for you?
These are normally supervisory functions, where they can be used to cancel tasks running at a different terminals. CSMT is used to update PPT. But I never had much chance to use them.
11. What transaction will you use to debug a CICS Program?
CEDF, which means CICS Execution Diagnostic facility.
12. What XCTL and LINK command is used for?
XCTL command transfers control to another program without setting up a return mechanism whereas the LINK command transfers control to next logical lower level with a return mechanism
13. Why the EXEC CICS HANDLE command is used?
It is used to specify what action the program needs to take when certain exceptional conditions occur.
14. Why the EXEC CICS RETURN command is used?
It is used simply to return control to CICS with no option and the terminal session ends.
15. What are the parameters will you use to code a SEND MAP command?
SEND MAP(name of the map)
MAPSET(name of the mapset which contains the specific map)
FROM(specifies the symbolic map)
MAPONLY(specifies dataonly needs to be sent)
DATAONLY(specifies that only data from the symbolic map needs to be sent)
ERASE/ERASEUP
CURSOR
16. How do you terminate each CICS commands?
EXEC CICS
intermediate commands
END-EXEC.
17. How do you obtain the storage dump from CICS?
CICS automatically adds the storage dump to a special file called dump data set. When the CICS is terminated, the dumps are automatically printed. The DSN can be found from the respective installation personnel.
18. What is the meaning for AEI9 CICS abend?
MAPFAIL.
19. What are the following entities represent?
EIBAID It is an one character field that indicates which attention key was used for the last RECEIVE command.
EIBTRMID This field supplies the name of the terminal running the task.
EIBCALEN This field represents the length of the communication area passed to my program. If no commarea is passed, it is set to zero.
20. How do you logoff from a CICS transaction?
Blank the screen, then type CSSF LOGOFF.
Motorola Interview Questions asked at Campus Interview
Motorola Interview Questions asked at Campus Interview
1. To reverse a string using a recursive function, without swapping or using an extra memory.
2. To reverse a linked list as above. given a macro like
define MAX(A,B) {to return that is larger}
what will MAX(i++,j),MAX(i,j++) return.
3. Difference between Macro and ordinary definition. Difference between Class and Struct.
4. Testing and Maintenance.(will you work in it and what are they) Give the outputs of a compiler and assembler and loader and linker etc. If a new data structure, suppose a queue is to be added like int, long etc., where shall the changes be -- lex or yacc or where.
5. what is a Real Time OS.Name some.
6. Describe VRTX in few words.
7. How does the scheduler know the time how it should be scheduled
8. sockets, TLI, streams.. and much about project
9. What is deadlock? How do you avoid it?
10. What is a semaphore?
11. What exactly happens after each system call in sockets, both at the client and at the server.
12. What is the difference between widget & gadget in XWindows?
13. Tell about strtok & strstr functions.
1. To reverse a string using a recursive function, without swapping or using an extra memory.
2. To reverse a linked list as above. given a macro like
define MAX(A,B) {to return that is larger}
what will MAX(i++,j),MAX(i,j++) return.
3. Difference between Macro and ordinary definition. Difference between Class and Struct.
4. Testing and Maintenance.(will you work in it and what are they) Give the outputs of a compiler and assembler and loader and linker etc. If a new data structure, suppose a queue is to be added like int, long etc., where shall the changes be -- lex or yacc or where.
5. what is a Real Time OS.Name some.
6. Describe VRTX in few words.
7. How does the scheduler know the time how it should be scheduled
8. sockets, TLI, streams.. and much about project
9. What is deadlock? How do you avoid it?
10. What is a semaphore?
11. What exactly happens after each system call in sockets, both at the client and at the server.
12. What is the difference between widget & gadget in XWindows?
13. Tell about strtok & strstr functions.
Qualcomm Interview Questions for Engineers
Initial round at Qualcomm Interview
1. How can you defined OOP?
2. How can you use OOP in your projects/products/applications?
3. What is copy constructor?
4. How many types of copy constructor are there?
5. What shallow copy constructor does/behaves?
6. Does C++ support copy constructor?
7. Does Java support copy constructor?
8. (If the answer to the previous question was correct) Why doesn’t Java support copy constructor?
9. What is software life cycle?
Next Interview
What was your experience in ASIC design?
Questions about analog circuits?
Design a lift control system and make it foolproof.?
why or why not use direct conversion systems?
Some Questions on
1)Data structures and bitwise questions
2)vmalloc, kalloc, volatile, constant, and memory management
3) Operating system questions in kernel.
Data structures(linked list), algorithms and OS questions
How would you implement dynamic memory allocation without using malloc?
There is a body of water that starts with 1 square unit, and doubles in size every day (2 units after 2 days, 4 units after 4 days). It takes 100 days to fill up. How many days would it take to fill if you started with 2 square units?
Was asked to write a code to count the number of set bits in a 32 bit interger?
1) Lets say that I have a continuous bit pattern of 1's and there is a1 ms glitch of 0's. How do I capture the glitch and display a stationary image of it? (assuming that 1 ms is too fast for out eyes to appreciably notice the change)
2) What are the four properties of a PN sequence?
3) Why do most hardware testers use stacks in their programs to store data?
1. How can you defined OOP?
2. How can you use OOP in your projects/products/applications?
3. What is copy constructor?
4. How many types of copy constructor are there?
5. What shallow copy constructor does/behaves?
6. Does C++ support copy constructor?
7. Does Java support copy constructor?
8. (If the answer to the previous question was correct) Why doesn’t Java support copy constructor?
9. What is software life cycle?
Next Interview
What was your experience in ASIC design?
Questions about analog circuits?
Design a lift control system and make it foolproof.?
why or why not use direct conversion systems?
Some Questions on
1)Data structures and bitwise questions
2)vmalloc, kalloc, volatile, constant, and memory management
3) Operating system questions in kernel.
Data structures(linked list), algorithms and OS questions
How would you implement dynamic memory allocation without using malloc?
There is a body of water that starts with 1 square unit, and doubles in size every day (2 units after 2 days, 4 units after 4 days). It takes 100 days to fill up. How many days would it take to fill if you started with 2 square units?
Was asked to write a code to count the number of set bits in a 32 bit interger?
1) Lets say that I have a continuous bit pattern of 1's and there is a1 ms glitch of 0's. How do I capture the glitch and display a stationary image of it? (assuming that 1 ms is too fast for out eyes to appreciably notice the change)
2) What are the four properties of a PN sequence?
3) Why do most hardware testers use stacks in their programs to store data?
Aricent Interview Questions at Campus
Aricent Interview Questions at Campus
1)What type of microprocessors do you know?8085 ,8086
2)Differentiate 8085 and 8086?
3)Draw Architecture of 8085 Microprocessor?
4)Do you know Data structures?Tell me what you know ?Linked list and Array Difference?
5)Explain me the concept of OOPs?
6)What is Inheritance?How it will be used in realworld?
7)What is Copy constructer?
8)Differentiate Constructer and Copycontructers ?in which scerarios they are used?
9)what are the different types of counter?
10)Difference Between C++ and Java?
1)What type of microprocessors do you know?8085 ,8086
2)Differentiate 8085 and 8086?
3)Draw Architecture of 8085 Microprocessor?
4)Do you know Data structures?Tell me what you know ?Linked list and Array Difference?
5)Explain me the concept of OOPs?
6)What is Inheritance?How it will be used in realworld?
7)What is Copy constructer?
8)Differentiate Constructer and Copycontructers ?in which scerarios they are used?
9)what are the different types of counter?
10)Difference Between C++ and Java?
Erwin datamodeling tool Basics
Erwin datamodeling tool Basics
All Fusion Erwin Data Modeler commonly known as Erwin, is a powerful and leading data modeling tool from Computer Associates. Computer Associates delivers several softwares for enterprise management, storage management solutions, security solutions, application life cycle management, data management and business intelligence.
Erwin makes database creation very simple by generating the DDL(sql) scripts from a data model by using its Forward Engineering technique or Erwin can be used to create data models from the existing database by using its Reverse Engineering technique.
Erwin workplace consists of the following main areas:
1) Logical: In this view, data model represents business requirements like entities, attributes etc.
2) Physical: In this view, data model represents physical structures like tables, columns, datatypes etc.
3)Modelmart: Many users can work with a same data model concurrently.
What can be done with Erwin?
* Logical, Physical and dimensional data models can be created.
* Data Models can be created from existing systems(rdbms, dbms, files etc.).
* Different versions of a data model can be compared.
* Data model and database can be compared.
* SQl scripts can be generated to create databases from data model.
* Reports can be generated in different file formats like .html, .rtf, and .txt.
* Data models can be opened and saved in several different file types like .er1, .ert, .bpx, .xml, .ers, .sql, .cmt, .df, .dbf, and .mdb files.
By using ModelMart, concurrent users can work on the same data model.
In order to create data models in Erwin, you need to have this All Fusion Erwin Data Modeler installed in your system. If you have installed Modelmart, then more than one user can work on the same model.
All Fusion Erwin Data Modeler commonly known as Erwin, is a powerful and leading data modeling tool from Computer Associates. Computer Associates delivers several softwares for enterprise management, storage management solutions, security solutions, application life cycle management, data management and business intelligence.
Erwin makes database creation very simple by generating the DDL(sql) scripts from a data model by using its Forward Engineering technique or Erwin can be used to create data models from the existing database by using its Reverse Engineering technique.
Erwin workplace consists of the following main areas:
1) Logical: In this view, data model represents business requirements like entities, attributes etc.
2) Physical: In this view, data model represents physical structures like tables, columns, datatypes etc.
3)Modelmart: Many users can work with a same data model concurrently.
What can be done with Erwin?
* Logical, Physical and dimensional data models can be created.
* Data Models can be created from existing systems(rdbms, dbms, files etc.).
* Different versions of a data model can be compared.
* Data model and database can be compared.
* SQl scripts can be generated to create databases from data model.
* Reports can be generated in different file formats like .html, .rtf, and .txt.
* Data models can be opened and saved in several different file types like .er1, .ert, .bpx, .xml, .ers, .sql, .cmt, .df, .dbf, and .mdb files.
By using ModelMart, concurrent users can work on the same data model.
In order to create data models in Erwin, you need to have this All Fusion Erwin Data Modeler installed in your system. If you have installed Modelmart, then more than one user can work on the same model.
Data Modeling Tools
Data Modeling Tools
There are a number of data modeling tools to transform business requirements into logical data model, and logical data model to physical data model. From physical data model, these tools can be instructed to generate sql code for creating database.
Few Datamodelling tools
Tool Name Company Name
Erwin Computer Associates
Embarcadero Embarcadero Technologies
Rational Rose IBM Corporation
Power Designer Sybase Corporation
Oracle Designer Oracle Corporation
Xcase RESolution LTD.
There are a number of data modeling tools to transform business requirements into logical data model, and logical data model to physical data model. From physical data model, these tools can be instructed to generate sql code for creating database.
Few Datamodelling tools
Tool Name Company Name
Erwin Computer Associates
Embarcadero Embarcadero Technologies
Rational Rose IBM Corporation
Power Designer Sybase Corporation
Oracle Designer Oracle Corporation
Xcase RESolution LTD.
What is Data Modeling
What is Data Modeling
A Data model is a conceptual representation of data structures(tables) required for a database and is very powerful in expressing and communicating the business requirements.
A data model visually represents the nature of data, business rules governing the data, and how it will be organized in the database. A data model is comprised of two parts logical design and physical design.
Data model helps functional and technical team in designing the database. Functional team normally refers to one or more Business Analysts, Business Managers, Smart Management Experts, End Users etc., and Technical teams refers to one or more programmers, DBAs etc. Data modelers are responsible for designing the data model and they communicate with functional team to get the business requirements and technical teams to implement the database.
The concept of data modeling can be better understood if we compare the development cycle of a data model to the construction of a house.
For example Company ABC is planning to build a guest house(database) and it calls the building architect(data modeler) and projects its building requirements (business requirements). Building architect(data modeler) develops the plan (data model) and gives it to company ABC. Finally company ABC calls civil engineers(DBA) to construct the guest house(database).
Need for developing a Data Model:
* A new application for OLTP(Online Transaction Processing), ODS(Operational Data Store), data warehouse and data marts.
* Rewriting data models from existing systems that may need to change reports.
* Incorrect data modeling in the existing systems.
* A data base that has no data models.
Advantages and Importance of Data Model
* The goal of a data model is to make sure that all data objects provided by the functional team are completely and accurately represented.
* Data model is detailed enough to be used by the technical team for building the physical database.
* The information contained in the data model will be used to define the significance of business, relational tables, primary and foreign keys, stored procedures, and triggers.
* Data Model can be used to communicate the business within and across businesses.
A Data model is a conceptual representation of data structures(tables) required for a database and is very powerful in expressing and communicating the business requirements.
A data model visually represents the nature of data, business rules governing the data, and how it will be organized in the database. A data model is comprised of two parts logical design and physical design.
Data model helps functional and technical team in designing the database. Functional team normally refers to one or more Business Analysts, Business Managers, Smart Management Experts, End Users etc., and Technical teams refers to one or more programmers, DBAs etc. Data modelers are responsible for designing the data model and they communicate with functional team to get the business requirements and technical teams to implement the database.
The concept of data modeling can be better understood if we compare the development cycle of a data model to the construction of a house.
For example Company ABC is planning to build a guest house(database) and it calls the building architect(data modeler) and projects its building requirements (business requirements). Building architect(data modeler) develops the plan (data model) and gives it to company ABC. Finally company ABC calls civil engineers(DBA) to construct the guest house(database).
Need for developing a Data Model:
* A new application for OLTP(Online Transaction Processing), ODS(Operational Data Store), data warehouse and data marts.
* Rewriting data models from existing systems that may need to change reports.
* Incorrect data modeling in the existing systems.
* A data base that has no data models.
Advantages and Importance of Data Model
* The goal of a data model is to make sure that all data objects provided by the functional team are completely and accurately represented.
* Data model is detailed enough to be used by the technical team for building the physical database.
* The information contained in the data model will be used to define the significance of business, relational tables, primary and foreign keys, stored procedures, and triggers.
* Data Model can be used to communicate the business within and across businesses.
Why grep is used? options of grep
Why grep is used? options of grep
Search for the occurence of a pattern in a file: grep 'pattern' file. If one just wants to know how often soemthing occurs in a file, then: grep -c 'pattern file. This can be used in a script like:
if [[ $(grep -c 'pattern' file) != 0 ]];then ......;fi. The condition is fullfilled if the pattern was found.
Grep Options
SYNTAX
grep"Search String" [filename]
grep[-e pattern] [file...]
grep[-f file] [file...]
Search for the occurence of a pattern in a file: grep 'pattern' file. If one just wants to know how often soemthing occurs in a file, then: grep -c 'pattern file. This can be used in a script like:
if [[ $(grep -c 'pattern' file) != 0 ]];then ......;fi. The condition is fullfilled if the pattern was found.
Grep Options
SYNTAX
grep
grep
grep
Korn shell Tutorials :Read input from user,Files
Korn shell Tutorials :Read input from user,Files
Read in a Variable
From a user we read with: read var. Then the users can type something in. One should first print something like: print -n "Enter your favorite haircolor: ";read var; print "". The -n suppresses the newline sign.
Read into a File Line for Line
To get each line of a file into a variable iteratively do:
{ while read myline;do
# process $myline
done } < filename
To catch the output of a pipeline each line at a time in a variable use:
last |sort
{
while read myline;do
# commands
done }
Read in a Variable
From a user we read with: read var. Then the users can type something in. One should first print something like: print -n "Enter your favorite haircolor: ";read var; print "". The -n suppresses the newline sign.
Read into a File Line for Line
To get each line of a file into a variable iteratively do:
{ while read myline;do
# process $myline
done } < filename
To catch the output of a pipeline each line at a time in a variable use:
last |sort
{
while read myline;do
# commands
done }
Korn shell Tutorials :Pipes and Coprocesses
Korn shell Tutorials :Pipes and Coprocesses
PIPES
For a serial processing of data from one command to the next do:
command1|command2|command3 ...
e.g. last |awk '{print $1}' |sort -u.
Coprocesses
One can have one background process with which one can comunicate with read -p and print -p. It is started with command |&. If one uses: ksh & then this shell in the background will do everything for us even telnet and so on: print -p "telnet hostname".
PIPES
For a serial processing of data from one command to the next do:
command1|command2|command3 ...
e.g. last |awk '{print $1}' |sort -u.
Coprocesses
One can have one background process with which one can comunicate with read -p and print -p. It is started with command |&. If one uses: ksh & then this shell in the background will do everything for us even telnet and so on: print -p "telnet hostname".
Korn shell Tutorials :Data Redirection
Korn shell Tutorials :Data Redirection
General
Data redirection is done with the follwoing signs: > >> < <<. Every program has at least a
standardinput, standardoutput and standarderroroutput. All of these can be redirected.
Command Output to File
For writing into a new file or for overwriting a file do: command > file
For appending to a file do: command >> file
Standard Error Redirection
To redirect the error output of a command do: command 2> file
To discard the error alltogether do: command 2>/dev/null
To put the error to the same location as the normal output do: command 2>&1
File into Command
If a program needs a file for input over standard input do: command < file
Combine Input and Output Redirection
command < infile > outfile
command < infile > outfile 2>/dev/null
Commands into Program ( Here Document )
Every unix command can take it's commands from a text like listing with:
command EOF
input1
input2
input3
EOF
From eof to eof all is feeded into the above mentioned command.
General
Data redirection is done with the follwoing signs: > >> < <<. Every program has at least a
standardinput, standardoutput and standarderroroutput. All of these can be redirected.
Command Output to File
For writing into a new file or for overwriting a file do: command > file
For appending to a file do: command >> file
Standard Error Redirection
To redirect the error output of a command do: command 2> file
To discard the error alltogether do: command 2>/dev/null
To put the error to the same location as the normal output do: command 2>&1
File into Command
If a program needs a file for input over standard input do: command < file
Combine Input and Output Redirection
command < infile > outfile
command < infile > outfile 2>/dev/null
Commands into Program ( Here Document )
Every unix command can take it's commands from a text like listing with:
command EOF
input1
input2
input3
EOF
From eof to eof all is feeded into the above mentioned command.
Korn shell Tutorials :Writing Functions
Korn shell Tutorials :Writing Functions
Description
A function (= procedure) must be defined before it is called, because ksh is interpreted at run time.
It knows all the variables from the calling shell except the commandline arguments. But has it's
own command line arguments so that one can call it with different values from different places in
the script. It has an exit status but cannot return a value like a c funcition can.
Making a Function
One can make one in either of the following two ways:
function foo {
# commands...
}
foo(){
# commands...
}
Calling the Function
To call it just put it's name in the script: foo. To give it arguments do: foo arg1 arg2 ...
The arguments are there in the form of $1...$n and $* for all at once like in the main code.
And the main $1 is not influenced bye the $1 of a particular function.
Return
The return statement exits the function imediately with the specified return value as an exit status.
Description
A function (= procedure) must be defined before it is called, because ksh is interpreted at run time.
It knows all the variables from the calling shell except the commandline arguments. But has it's
own command line arguments so that one can call it with different values from different places in
the script. It has an exit status but cannot return a value like a c funcition can.
Making a Function
One can make one in either of the following two ways:
function foo {
# commands...
}
foo(){
# commands...
}
Calling the Function
To call it just put it's name in the script: foo. To give it arguments do: foo arg1 arg2 ...
The arguments are there in the form of $1...$n and $* for all at once like in the main code.
And the main $1 is not influenced bye the $1 of a particular function.
Return
The return statement exits the function imediately with the specified return value as an exit status.
Korn shell Tutorials :Regular Expressions
Korn shell Tutorials :Regular Expressions
Ksh has it's own regular expressions.
Use an * for any string. So to get all the files ending it .c use *.c.
A single character is represented with a ?. So all the files starting with any sign followed bye 44.f can be fetched by: ?44.f.
Especially in ksh there are quantifiers for whole patterns:
?(pattern) matches zero or one times the pattern.
*(pattern) matches any time the pattern.
+(pattern) matches one or more time the pattern.
@(pattern) matches one time the pattern.
!(pattern) matches string without the pattern.
So one can question a string in a variable like: if [[ $var = fo@(?4*67).c ]];then ...
Ksh has it's own regular expressions.
Use an * for any string. So to get all the files ending it .c use *.c.
A single character is represented with a ?. So all the files starting with any sign followed bye 44.f can be fetched by: ?44.f.
Especially in ksh there are quantifiers for whole patterns:
?(pattern) matches zero or one times the pattern.
*(pattern) matches any time the pattern.
+(pattern) matches one or more time the pattern.
@(pattern) matches one time the pattern.
!(pattern) matches string without the pattern.
So one can question a string in a variable like: if [[ $var = fo@(?4*67).c ]];then ...
Korn shell Tutorials :Manipulating the variables
Korn shell Tutorials :Manipulating the variables
Removing something from a variable
Variables that contain a path can very easily be stripped of it: ${name##*/} gives you just the filename.
Or if one wants the path: ${name%/*}. % takes it away from the left and # from the right.
%% and ## take the longest possibility while % and # just take the shortest one.
Replacing a variable if it does not yet exits
If we wanted $foo or if not set 4 then: ${foo:-4} but it still remains unset. To change that we use:
${foo:=4}
Exiting and stating something if variable is not set
This is very important if our program relays on a certain vaiable: ${foo:?"foo not set!"}
Just check for the variable
${foo:+1} gives one if $foo is set, otherwise nothing.
Removing something from a variable
Variables that contain a path can very easily be stripped of it: ${name##*/} gives you just the filename.
Or if one wants the path: ${name%/*}. % takes it away from the left and # from the right.
%% and ## take the longest possibility while % and # just take the shortest one.
Replacing a variable if it does not yet exits
If we wanted $foo or if not set 4 then: ${foo:-4} but it still remains unset. To change that we use:
${foo:=4}
Exiting and stating something if variable is not set
This is very important if our program relays on a certain vaiable: ${foo:?"foo not set!"}
Just check for the variable
${foo:+1} gives one if $foo is set, otherwise nothing.
Korn shell Tutorials :Comparision in scripting
Korn shell Tutorials :Comparision in scripting
To compare strings one uses "=" for equal and "!=" for not equal.
To compare numbers one uses "-eq" for equal "-ne" for not equal as well as "-gt" for greater than
and "-lt" for less than.
if [[ $name = "John" ]];then
# commands....
fi
if [[ $size -eq 1000 ]];then
# commands....
fi
With "&&" for "AND" and "||" for "OR" one can combine statements:
if [[ $price -lt 1000
$name = "Hanna" ]];then
# commands....
fi
if [[ $name = "Fred" && $city = "Denver" ]];then
# commands....
fi
To compare strings one uses "=" for equal and "!=" for not equal.
To compare numbers one uses "-eq" for equal "-ne" for not equal as well as "-gt" for greater than
and "-lt" for less than.
if [[ $name = "John" ]];then
# commands....
fi
if [[ $size -eq 1000 ]];then
# commands....
fi
With "&&" for "AND" and "||" for "OR" one can combine statements:
if [[ $price -lt 1000
$name = "Hanna" ]];then
# commands....
fi
if [[ $name = "Fred" && $city = "Denver" ]];then
# commands....
fi
Ksh Tutorials :Command Line Arguments in kshell
Ksh Tutorials :Command Line Arguments in kshell
It is also called "positional parameters"
The number of command line arguments is stored in $# so one can check
for arguments with:
if [[ $# -eq 0 ]];then
print "No Arguments"
exit
fi
The single Arguments are stored in $1, ....$n and all are in $* as one string. The arguments cannot
directly be modified but one can reset the hole commandline for another part of the program.
If we need a first argument $first for the rest of the program we do:
if [[ $1 != $first ]];then
set $first $*
fi
One can iterate over the command line arguments with the help of the shift command. Shift indirectly removes the first argument.
until [[ $# -qe 0 ]];do
# commands ....
shift
done
One can also iterate with the for loop, the default with for is $*:
for arg;do
print $arg
done
The program name is stored in $0 but it contains the path also!
It is also called "positional parameters"
The number of command line arguments is stored in $# so one can check
for arguments with:
if [[ $# -eq 0 ]];then
print "No Arguments"
exit
fi
The single Arguments are stored in $1, ....$n and all are in $* as one string. The arguments cannot
directly be modified but one can reset the hole commandline for another part of the program.
If we need a first argument $first for the rest of the program we do:
if [[ $1 != $first ]];then
set $first $*
fi
One can iterate over the command line arguments with the help of the shift command. Shift indirectly removes the first argument.
until [[ $# -qe 0 ]];do
# commands ....
shift
done
One can also iterate with the for loop, the default with for is $*:
for arg;do
print $arg
done
The program name is stored in $0 but it contains the path also!
Ksh Tutorials :for loop in kshell programming
Ksh Tutorials :for loop in kshell programming
while do done
while [[ $count -gt 0 ]];do
print "\$count is $count"
(( count -= 1 ))
done
until do done
until [[ $answer = "yes" ]];do
print -n "Please enter \"yes\": "
read answer
print ""
done
for var in list do done
for foo in $(ls);do
if [[ -d $foo ]];then
print "$foo is a directory"
else
print "$foo is not a directory"
fi
done
continue...break
One can skip the rest of a loop and directly go to the next iteration with: "continue".
while read line
do
if [[ $line = *.gz ]];then
continue
else
print $line
fi
done
One can also prematurely leave a loop with: "break".
while read line;do
if [[ $line = *!(.c) ]];then
break
else
print $line
fi
done
while do done
while [[ $count -gt 0 ]];do
print "\$count is $count"
(( count -= 1 ))
done
until do done
until [[ $answer = "yes" ]];do
print -n "Please enter \"yes\": "
read answer
print ""
done
for var in list do done
for foo in $(ls);do
if [[ -d $foo ]];then
print "$foo is a directory"
else
print "$foo is not a directory"
fi
done
continue...break
One can skip the rest of a loop and directly go to the next iteration with: "continue".
while read line
do
if [[ $line = *.gz ]];then
continue
else
print $line
fi
done
One can also prematurely leave a loop with: "break".
while read line;do
if [[ $line = *!(.c) ]];then
break
else
print $line
fi
done
Ksh Tutorials :if else Branching
Ksh Tutorials :if else Branching
if then fi
if [[ $value -eq 7 ]];then
print "$value is 7"
fi
or:
if [[ $value -eq 7 ]]
then
print "$value is 7"
fi
or:
if [[ $value -eq 7 ]];then print "$value is 7";fi
if then else fi
if [[ $name = "John" ]];then
print "Your welcome, ${name}."
else
print "Good bye, ${name}!"
fi
if then elif then else fi
if [[ $name = "John" ]];then
print "Your welcome, ${name}."
elif [[ $name = "Hanna" ]];then
print "Hello, ${name}, who are you?"
else
print "Good bye, ${name}!"
fi
Case esac
case $var in
john
fred) print $invitation;;
martin) print $declination;;
*) print "Wrong name...";;
esac
if then fi
if [[ $value -eq 7 ]];then
print "$value is 7"
fi
or:
if [[ $value -eq 7 ]]
then
print "$value is 7"
fi
or:
if [[ $value -eq 7 ]];then print "$value is 7";fi
if then else fi
if [[ $name = "John" ]];then
print "Your welcome, ${name}."
else
print "Good bye, ${name}!"
fi
if then elif then else fi
if [[ $name = "John" ]];then
print "Your welcome, ${name}."
elif [[ $name = "Hanna" ]];then
print "Hello, ${name}, who are you?"
else
print "Good bye, ${name}!"
fi
Case esac
case $var in
john
fred) print $invitation;;
martin) print $declination;;
*) print "Wrong name...";;
esac
Ksh Tutorials :Declaring Variables
Ksh Tutorials :Declaring Variables
Filling in
When filling into a variable then one uses just it's name: state="US" and no blanks. There is no difference between strings and numbers: price=50.
Using
When using a variable one needs to put a $ sign in front of it: print $state $price.
Arrays
Set and use an array like:
arrname[1]=4 To fill in
print ${arraname[1]} To print out
${arrname[*]} Get all elements
${#arrname[*]} Get the number of elements
Declaration
There are happily no declarations of variables needed in ksh. One cannot have decimals only integers.
Filling in
When filling into a variable then one uses just it's name: state="US" and no blanks. There is no difference between strings and numbers: price=50.
Using
When using a variable one needs to put a $ sign in front of it: print $state $price.
Arrays
Set and use an array like:
arrname[1]=4 To fill in
print ${arraname[1]} To print out
${arrname[*]} Get all elements
${#arrname[*]} Get the number of elements
Declaration
There are happily no declarations of variables needed in ksh. One cannot have decimals only integers.
Ksh Tutorials :Basics of shell scripting
Kshell Tutorials :Basics of shell scripting
Defining the Shell Type
To make a ksh script (which is a ksh program) crate a new file with a starting line like:
#!/usr/bin/ksh
It is important that the path to the ksh is propper and that the line doesn not have more than 32 characters. The shell from which you are starting the script will find this line and and hand the whole script over to to ksh. Without this line the script would be interpreted by the same typ of shell as the one, from which it was started. But since the syntax is different for all shells, it is necessary to define the shell with that line.
Four Types of Lines
A script has four types of lines: The shell defining line at the top, empty lines, commentary lines starting with a # and command lines. See the following top of a script as an example for these types of lines:
#!/usr/bin/ksh
# Commentary......
file=/path/file
if [[ $file = $1 ]];then
command
fi
Start and End of Script
The script starts at the first line and ends either when it encounters an "exit" or the last line. All "#" lines are ignored.
Start and End of Command
A command starts with the first word on a line or if it's the second command on a line with the first word after a";'.
A command ends either at the end of the line or whith a ";". So one can put several commands onto one line:
print -n "Name: "; read name; print ""
One can continue commands over more than one line with a "\" immediately followed by a newline sign which is made be the return key:
grep filename
sort -u
awk '{print $4}'
\
uniq -c >> /longpath/file
Name and Permissions of Script File
The script mus not have a name which is identical to a unix command: So the script must NOT be called "test"!
After saveing the file give it the execute permissions with: chmod 700 filename.
Defining the Shell Type
To make a ksh script (which is a ksh program) crate a new file with a starting line like:
#!/usr/bin/ksh
It is important that the path to the ksh is propper and that the line doesn not have more than 32 characters. The shell from which you are starting the script will find this line and and hand the whole script over to to ksh. Without this line the script would be interpreted by the same typ of shell as the one, from which it was started. But since the syntax is different for all shells, it is necessary to define the shell with that line.
Four Types of Lines
A script has four types of lines: The shell defining line at the top, empty lines, commentary lines starting with a # and command lines. See the following top of a script as an example for these types of lines:
#!/usr/bin/ksh
# Commentary......
file=/path/file
if [[ $file = $1 ]];then
command
fi
Start and End of Script
The script starts at the first line and ends either when it encounters an "exit" or the last line. All "#" lines are ignored.
Start and End of Command
A command starts with the first word on a line or if it's the second command on a line with the first word after a";'.
A command ends either at the end of the line or whith a ";". So one can put several commands onto one line:
print -n "Name: "; read name; print ""
One can continue commands over more than one line with a "\" immediately followed by a newline sign which is made be the return key:
grep filename
sort -u
awk '{print $4}'
\
uniq -c >> /longpath/file
Name and Permissions of Script File
The script mus not have a name which is identical to a unix command: So the script must NOT be called "test"!
After saveing the file give it the execute permissions with: chmod 700 filename.
Facebook Interview Questions for Software Engineer
Facebook Interview Questions for Software Engineer
1)Write a Program to compute squareroot of number?
2)Shuffle an array of size n such that each element has 1/n probability to remain in its original spot. The best solution has O(n) complexity?
3)Write a sql to find all the duplicate email address in a table which contains only one column "email"?
4)Write a Program to reverse each word in a string?
5)Write a program to evaluate a simple mathematical expression like 4 + 2*a/b - 3?
6)Write a Program to rotate a matrix by 90 degrees?
7)Write a program to revese a linklist?
8)What is the difference between Statically and Dynamically typed Language?
9)Tell me a Problem you faced while implementing a algorithm and how did you solve it?Show it pictoriallly?
10)Write a Program that removes duplicate characters in a String?
11)Write code for finding length of largest monotonically increasing sequence in an array of integers.
Optimize it (not the usual O(n) in worst case, but a better approach in average case)?
1)Write a Program to compute squareroot of number?
2)Shuffle an array of size n such that each element has 1/n probability to remain in its original spot. The best solution has O(n) complexity?
3)Write a sql to find all the duplicate email address in a table which contains only one column "email"?
4)Write a Program to reverse each word in a string?
5)Write a program to evaluate a simple mathematical expression like 4 + 2*a/b - 3?
6)Write a Program to rotate a matrix by 90 degrees?
7)Write a program to revese a linklist?
8)What is the difference between Statically and Dynamically typed Language?
9)Tell me a Problem you faced while implementing a algorithm and how did you solve it?Show it pictoriallly?
10)Write a Program that removes duplicate characters in a String?
11)Write code for finding length of largest monotonically increasing sequence in an array of integers.
Optimize it (not the usual O(n) in worst case, but a better approach in average case)?
Apple Company Interview Questions for Software Engineer
Apple Company Interview Questions for Software Engineer
1)What is a Deadlock, can you give some examples of real world scenarios where deadlock happens ?
2)I am trying to merge into a freeway which is completely backed up and cars are moving very slow, is this a deadlock ? If you had to assign a computer science term to this scenarios what would be the closest thing that comes to your mind ?
3)Write a Java program (which uses no external storage) that prints "Register Now !" for the first 30 days of its use. After the 30th day it should print "Free Trial Expired!"?
4)What is the main reason for using pass by reference over pass by pointer?
5)How do you detect a deadlock?
6)If a browser is crashed how do you debug?
7)How tcp and udp protocols work? and how they together react?
8)Write atoi Program?
9)How to make Multicasting reliable?
10)How to know weather linked list is circular or not?
11)Difference between C++ array and STL Array?
12)Write some test cases for Iphone browser?
13)Given an array of integers, write a function to find the 2nd max value. Write test cases?
14)How would you traverse a linked list with complexity O(n^0.5)?
15)Write a program to convert hexa decimal number to integer value?
16)Tell me a bout Garbage collecter?Explain Mark &Sweep Algorithm?
1)What is a Deadlock, can you give some examples of real world scenarios where deadlock happens ?
2)I am trying to merge into a freeway which is completely backed up and cars are moving very slow, is this a deadlock ? If you had to assign a computer science term to this scenarios what would be the closest thing that comes to your mind ?
3)Write a Java program (which uses no external storage) that prints "Register Now !" for the first 30 days of its use. After the 30th day it should print "Free Trial Expired!"?
4)What is the main reason for using pass by reference over pass by pointer?
5)How do you detect a deadlock?
6)If a browser is crashed how do you debug?
7)How tcp and udp protocols work? and how they together react?
8)Write atoi Program?
9)How to make Multicasting reliable?
10)How to know weather linked list is circular or not?
11)Difference between C++ array and STL Array?
12)Write some test cases for Iphone browser?
13)Given an array of integers, write a function to find the 2nd max value. Write test cases?
14)How would you traverse a linked list with complexity O(n^0.5)?
15)Write a program to convert hexa decimal number to integer value?
16)Tell me a bout Garbage collecter?Explain Mark &Sweep Algorithm?
Sap ABAP Faqs,Interview Questions
Sap ABAP Faqs,Interview Questions
What is an ABAP data dictionary?-
ABAP 4 data dictionary describes the logical structures of the objects used in application development and shows how they are mapped to the underlying relational database in tables/views.
What are domains and data element?-
Domains:Domain is the central object for describing the technical characteristics of an attribute of an business objects. It describes the value range of the field. Data Element: It is used to describe the semantic definition of the table fields like description the field. Data element describes how a field can be displayed to end-user.
What is foreign key relationship?
- A relationship which can be defined between tables and must be explicitly defined at field level. Foreign keys are used to ensure the consistency of data. Data entered should be checked against existing data to ensure that there are now contradiction. While defining foreign key relationship cardinality has to be specified. Cardinality mentions how many dependent records or how referenced records are possible.
Describe data classes.- Master data: It is the data which is seldomly changed. Transaction data: It is the data which is often changed. Organization data: It is a customizing data which is entered in the system when the system is configured and is then rarely changed. System data:It is the data which R/3 system needs for itself.
What are indexes?-
Indexes are described as a copy of a database table reduced to specific fields. This data exists in sorted form. This sorting form ease fast access to the field of the tables. In order that other fields are also read, a pointer to the associated record of the actual table are included in the index. Yhe indexes are activated along with the table and are created automatically with it in the database.
Difference between transparent tables and pooled tables.- Transparent tables: Transparent tables in the dictionary has a one-to-one relation with the table in database. Its structure corresponds to single database field. Table in the database has the same name as in the dictionary. Transparent table holds application data. Pooled tables. Pooled tables in the dictionary has a many-to-one relation with the table in database. Table in the database has the different name as in the dictionary. Pooled table are stored in table pool at the database level.
What is an ABAP/4 Query?- ABAP/4 Query is a powerful tool to generate simple reports without any coding. ABAP/4 Query can generate the following 3 simple reports: Basic List: It is the simple reports. Statistics: Reports with statistical functions like Average, Percentages. Ranked Lists: For analytical reports. - For creating a ABAP/4 Query, programmer has to create user group and a functional group. Functional group can be created using with or without logical database table. Finally, assign user group to functional group. Finally, create a query on the functional group generated.
What is BDC programming?- Transferring of large/external/legacy data into SAP system using Batch Input programming. Batch input is a automatic procedure referred to as BDC(Batch Data Communications).The central component of the transfer is a queue file which receives the data vie a batch input programs and groups associated data into “sessions”.
What are the functional modules used in sequence in BDC?- These are the 3 functional modules which are used in a sequence to perform a data transfer successfully using BDC programming: BDC_OPEN_GROUP - Parameters like Name of the client, sessions and user name are specified in this functional modules. BDC_INSERT - It is used to insert the data for one transaction into a session. BDC_CLOSE_GROUP - This is used to close the batch input session.
What are internal tables?- Internal tables are a standard data type object which exists only during the runtime of the program. They are used to perform table calculations on subsets of database tables and for re-organising the contents of database tables according to users need.
What is ITS? What are the merits of ITS?- ITS is a Internet Transaction Server. ITS forms an interface between HTTP server and R/3 system, which converts screen provided data by the R/3 system into HTML documents and vice-versa. Merits of ITS: A complete web transaction can be developed and tested in R/3 system. All transaction components, including those used by the ITS outside the R/3 system at runtime, can be stored in the R/3 system. The advantage of automatic language processing in the R/3 system can be utilized to language-dependent HTML documents at runtime.
What is DynPro?- DynPro is a Dynamic Programming which is a combination of screen and the associated flow logic Screen is also called as DynPro.
What are screen painter and menu painter?- Screen painter: Screen painter is a tool to design and maintain screen and its elements. It allows user to create GUI screens for the transactions. Attributes, layout, filed attributes and flow logic are the elements of Screen painter. Menu painter: Menu painter is a tool to design the interface components. Status, menu bars, menu lists, F-key settings, functions and titles are the components of Menu painters. Screen painter and menu painter both are the graphical interface of an ABAP/4 applications.
What are the components of SAP scripts?- SAP scripts is a word processing tool of SAP which has the following components: Standard text. It is like a standard normal documents. Layout sets. - Layout set consists of the following components: Windows and pages, Paragraph formats, Character formats. Creating forms in the R/3 system. Every layout set consists of Header, paragraph, and character string. ABAP/4 program.
What is ALV programming in ABAP? When is this grid used in ABAP?- ALV is Application List viewer. Sap provides a set of ALV (ABAP LIST VIEWER) function modules which can be put into use to embellish the output of a report. This set of ALV functions is used to enhance the readability and functionality of any report output. Cases arise in sap when the output of a report contains columns extending more than 255 characters in length. In such cases, this set of ALV functions can help choose selected columns and arrange the different columns from a report output and also save different variants for report display. This is a very efficient tool for dynamically sorting and arranging the columns from a report output. The report output can contain up to 90 columns in the display with the wide array of display options.
What are the events in ABAP/4 language?- Initialization, At selection-screen, Start-of-selection, end-of-selection, top-of-page, end-of-page, At line-selection, At user-command, At PF, Get, At New, At LAST, AT END, AT FIRST.
What is CTS and what do you know about it?- The Change and Transport System (CTS) is a tool that helps you to organize development projects in the ABAP Workbench and in Customizing, and then transport the changes between the SAP Systems and clients in your system landscape. This documentation provides you with an overview of how to manage changes with the CTS and essential information on setting up your system and client landscape and deciding on a transport strategy. Read and follow this documentation when planning your development project.
What are logical databases? What are the advantages/ dis-advantages of logical databases?- To read data from a database tables we use logical database. A logical database provides read-only access to a group of related tables to an ABAP/4 program. Advantages: i)check functions which check that user input is complete, correct,and plausible. ii)Meaningful data selection. iii)central authorization checks for database accesses. iv)good read access performance while retaining the hierarchical data view determined by the application logic. dis advantages: i)If you donot specify a logical database in the program attributes,the GET events never occur. ii)There is no ENDGET command,so the code block associated with an event ends with the next event statement (such as another GET or an END-OF-SELECTION).
What is a batch input session?- BATCH INPUT SESSION is an intermediate step between internal table and database table. Data along with the action is stored in session ie data for screen fields, to which screen it is passed, program name behind it, and how next screen is processed.
How to upload data using CATT ?- These are the steps to be followed to Upload data through CATT: Creation of the CATT test case & recording the sample data input. Download of the source file template. Modification of the source file. Upload of the data from the source file.
What is Smart Forms?- Smart Forms allows you to create forms using a graphical design tool with robust functionality, color, and more. Additionally, all new forms developed at SAP will be created with the new Smart Form solution.
How can I make a differentiation between dependent and independent data?- Client dependent or independent transfer requirements include client specific or cross client objects in the change requests. Workbench objects like SAPscripts are client specific, some entries in customizing are client independent. If you display the object list for one change request, and then for each object the object attributes, you will find the flag client specific. If one object in the task list has this flag on, then that transport will be client dependent.
What is the difference between macro and subroutine?- Macros can only be used in the program the are defined in and only after the definition are expanded at compilation / generation. Subroutines (FORM) can be called from both the program the are defined in and other programs . A MACRO is more or less an abbreviation for some lines of code that are used more than once or twice. A FORM is a local subroutine (which can be called external). A FUNCTION is (more or less) a subroutine that is called external. Since debugging a MACRO is not really possible, prevent the use of them (I’ve never used them, but seen them in action). If the subroutine is used only local (called internal) use a FORM. If the subroutine is called external (used by more than one program) use a FUNCTION.
What is an ABAP data dictionary?-
ABAP 4 data dictionary describes the logical structures of the objects used in application development and shows how they are mapped to the underlying relational database in tables/views.
What are domains and data element?-
Domains:Domain is the central object for describing the technical characteristics of an attribute of an business objects. It describes the value range of the field. Data Element: It is used to describe the semantic definition of the table fields like description the field. Data element describes how a field can be displayed to end-user.
What is foreign key relationship?
- A relationship which can be defined between tables and must be explicitly defined at field level. Foreign keys are used to ensure the consistency of data. Data entered should be checked against existing data to ensure that there are now contradiction. While defining foreign key relationship cardinality has to be specified. Cardinality mentions how many dependent records or how referenced records are possible.
Describe data classes.- Master data: It is the data which is seldomly changed. Transaction data: It is the data which is often changed. Organization data: It is a customizing data which is entered in the system when the system is configured and is then rarely changed. System data:It is the data which R/3 system needs for itself.
What are indexes?-
Indexes are described as a copy of a database table reduced to specific fields. This data exists in sorted form. This sorting form ease fast access to the field of the tables. In order that other fields are also read, a pointer to the associated record of the actual table are included in the index. Yhe indexes are activated along with the table and are created automatically with it in the database.
Difference between transparent tables and pooled tables.- Transparent tables: Transparent tables in the dictionary has a one-to-one relation with the table in database. Its structure corresponds to single database field. Table in the database has the same name as in the dictionary. Transparent table holds application data. Pooled tables. Pooled tables in the dictionary has a many-to-one relation with the table in database. Table in the database has the different name as in the dictionary. Pooled table are stored in table pool at the database level.
What is an ABAP/4 Query?- ABAP/4 Query is a powerful tool to generate simple reports without any coding. ABAP/4 Query can generate the following 3 simple reports: Basic List: It is the simple reports. Statistics: Reports with statistical functions like Average, Percentages. Ranked Lists: For analytical reports. - For creating a ABAP/4 Query, programmer has to create user group and a functional group. Functional group can be created using with or without logical database table. Finally, assign user group to functional group. Finally, create a query on the functional group generated.
What is BDC programming?- Transferring of large/external/legacy data into SAP system using Batch Input programming. Batch input is a automatic procedure referred to as BDC(Batch Data Communications).The central component of the transfer is a queue file which receives the data vie a batch input programs and groups associated data into “sessions”.
What are the functional modules used in sequence in BDC?- These are the 3 functional modules which are used in a sequence to perform a data transfer successfully using BDC programming: BDC_OPEN_GROUP - Parameters like Name of the client, sessions and user name are specified in this functional modules. BDC_INSERT - It is used to insert the data for one transaction into a session. BDC_CLOSE_GROUP - This is used to close the batch input session.
What are internal tables?- Internal tables are a standard data type object which exists only during the runtime of the program. They are used to perform table calculations on subsets of database tables and for re-organising the contents of database tables according to users need.
What is ITS? What are the merits of ITS?- ITS is a Internet Transaction Server. ITS forms an interface between HTTP server and R/3 system, which converts screen provided data by the R/3 system into HTML documents and vice-versa. Merits of ITS: A complete web transaction can be developed and tested in R/3 system. All transaction components, including those used by the ITS outside the R/3 system at runtime, can be stored in the R/3 system. The advantage of automatic language processing in the R/3 system can be utilized to language-dependent HTML documents at runtime.
What is DynPro?- DynPro is a Dynamic Programming which is a combination of screen and the associated flow logic Screen is also called as DynPro.
What are screen painter and menu painter?- Screen painter: Screen painter is a tool to design and maintain screen and its elements. It allows user to create GUI screens for the transactions. Attributes, layout, filed attributes and flow logic are the elements of Screen painter. Menu painter: Menu painter is a tool to design the interface components. Status, menu bars, menu lists, F-key settings, functions and titles are the components of Menu painters. Screen painter and menu painter both are the graphical interface of an ABAP/4 applications.
What are the components of SAP scripts?- SAP scripts is a word processing tool of SAP which has the following components: Standard text. It is like a standard normal documents. Layout sets. - Layout set consists of the following components: Windows and pages, Paragraph formats, Character formats. Creating forms in the R/3 system. Every layout set consists of Header, paragraph, and character string. ABAP/4 program.
What is ALV programming in ABAP? When is this grid used in ABAP?- ALV is Application List viewer. Sap provides a set of ALV (ABAP LIST VIEWER) function modules which can be put into use to embellish the output of a report. This set of ALV functions is used to enhance the readability and functionality of any report output. Cases arise in sap when the output of a report contains columns extending more than 255 characters in length. In such cases, this set of ALV functions can help choose selected columns and arrange the different columns from a report output and also save different variants for report display. This is a very efficient tool for dynamically sorting and arranging the columns from a report output. The report output can contain up to 90 columns in the display with the wide array of display options.
What are the events in ABAP/4 language?- Initialization, At selection-screen, Start-of-selection, end-of-selection, top-of-page, end-of-page, At line-selection, At user-command, At PF, Get, At New, At LAST, AT END, AT FIRST.
What is CTS and what do you know about it?- The Change and Transport System (CTS) is a tool that helps you to organize development projects in the ABAP Workbench and in Customizing, and then transport the changes between the SAP Systems and clients in your system landscape. This documentation provides you with an overview of how to manage changes with the CTS and essential information on setting up your system and client landscape and deciding on a transport strategy. Read and follow this documentation when planning your development project.
What are logical databases? What are the advantages/ dis-advantages of logical databases?- To read data from a database tables we use logical database. A logical database provides read-only access to a group of related tables to an ABAP/4 program. Advantages: i)check functions which check that user input is complete, correct,and plausible. ii)Meaningful data selection. iii)central authorization checks for database accesses. iv)good read access performance while retaining the hierarchical data view determined by the application logic. dis advantages: i)If you donot specify a logical database in the program attributes,the GET events never occur. ii)There is no ENDGET command,so the code block associated with an event ends with the next event statement (such as another GET or an END-OF-SELECTION).
What is a batch input session?- BATCH INPUT SESSION is an intermediate step between internal table and database table. Data along with the action is stored in session ie data for screen fields, to which screen it is passed, program name behind it, and how next screen is processed.
How to upload data using CATT ?- These are the steps to be followed to Upload data through CATT: Creation of the CATT test case & recording the sample data input. Download of the source file template. Modification of the source file. Upload of the data from the source file.
What is Smart Forms?- Smart Forms allows you to create forms using a graphical design tool with robust functionality, color, and more. Additionally, all new forms developed at SAP will be created with the new Smart Form solution.
How can I make a differentiation between dependent and independent data?- Client dependent or independent transfer requirements include client specific or cross client objects in the change requests. Workbench objects like SAPscripts are client specific, some entries in customizing are client independent. If you display the object list for one change request, and then for each object the object attributes, you will find the flag client specific. If one object in the task list has this flag on, then that transport will be client dependent.
What is the difference between macro and subroutine?- Macros can only be used in the program the are defined in and only after the definition are expanded at compilation / generation. Subroutines (FORM) can be called from both the program the are defined in and other programs . A MACRO is more or less an abbreviation for some lines of code that are used more than once or twice. A FORM is a local subroutine (which can be called external). A FUNCTION is (more or less) a subroutine that is called external. Since debugging a MACRO is not really possible, prevent the use of them (I’ve never used them, but seen them in action). If the subroutine is used only local (called internal) use a FORM. If the subroutine is called external (used by more than one program) use a FUNCTION.
Oracle Database Interview Questions,Faqs
Oracle Database Interview Questions,Faqs
What are the components of physical database structure of Oracle database?
Oracle database is comprised of three types of files. One or more datafiles, two are more redo log files, and one or more control files.
What are the components of logical database structure of Oracle database?
There are tablespaces and database's schema objects.
What is a tablespace?
A database is divided into Logical Storage Unit called tablespaces. A tablespace is used to grouped related logical structures together.
What is SYSTEM tablespace and when is it created?
Every Oracle database contains a tablespace named SYSTEM, which is automatically created when the database is created. The SYSTEM tablespace always contains the data dictionary tables for the entire database.
Explain the relationship among database, tablespace and data file ?
Each databases logically divided into one or more tablespaces one or more data files are explicitly created for each tablespace.
What is schema?
A schema is collection of database objects of a user.
What are Schema Objects?
Schema objects are the logical structures that directly refer to the database's data. Schema objects include tables, views, sequences, synonyms, indexes, clusters, database triggers, procedures, functions packages and database links.
Can objects of the same schema reside in different tablespaces?
Yes.
Can a tablespace hold objects from different schemes?
Yes.
What is Oracle table?
A table is the basic unit of data storage in an Oracle database. The tables of a database hold all of the user accessible data. Table data is stored in rows and columns.
What is an Oracle view?
A view is a virtual table. Every view has a query attached to it. (The query is a SELECT statement that identifies the columns and rows of the table(s) the view uses.)
What is Partial Backup ?
A Partial Backup is any operating system backup short of a full backup, taken while the database is open or shut down.
What is Mirrored on-line Redo Log ?
A mirrored on-line redo log consists of copies of on-line redo log files physically located on separate disks, changes made to one member of the group are made to all members.
What is Full Backup ?
A full backup is an operating system backup of all data files, on-line redo log files and control file that constitute ORACLE database and the parameter.
Can a View based on another View ?
Yes.
Can a Tablespace hold objects from different Schemes ?
Yes.
Can objects of the same Schema reside in different tablespace ?
Yes.
What is the use of Control File ?
When an instance of an ORACLE database is started, its control file is used to identify the database and redo log files that must be opened for database operation to proceed. It is also used in database recovery.
Do View contain Data ?
Views do not contain or store data.
What are the Referential actions supported by FOREIGN KEY integrity constraint ?
UPDATE and DELETE Restrict - A referential integrity rule that disallows the update or deletion of referenced data. DELETE Cascade - When a referenced row is deleted all associated dependent rows are deleted.
What are the type of Synonyms?
There are two types of Synonyms Private and Public.
What is a Redo Log ?
The set of Redo Log files YSDATE,UID,USER or USERENV SQL functions, or the pseudo columns LEVEL or ROWNUM.
What is an Index Segment ?
Each Index has an Index segment that stores all of its data.
Explain the relationship among Database, Tablespace and Data file?
Each databases logically divided into one or more tablespaces one or more data files are explicitly created for each tablespace
What are the different type of Segments ?
Data Segment, Index Segment, Rollback Segment and Temporary Segment.
What are Clusters ?
Clusters are groups of one or more tables physically stores together to share common columns and are often used together.
What is an Integrity Constrains ?
An integrity constraint is a declarative way to define a business rule for a column of a table.
What is an Index ?
An Index is an optional structure associated with a table to have direct access to rows, which can be created to increase the performance of data retrieval. Index can be created on one or more columns of a table.
What is an Extent ?
An Extent is a specific number of contiguous data blocks, obtained in a single allocation, and used to store a specific type of information.
What is a View ?
A view is a virtual table. Every view has a Query attached to it. (The Query is a SELECT statement that identifies the columns and rows of the table(s) the view uses.)
What is Table ?
A table is the basic unit of data storage in an ORACLE database. The tables of a database hold all of the user accessible data. Table data is stored in rows and columns.
What are the advantages of views?
- Provide an additional level of table security, by restricting access to a predetermined set of rows and columns of a table.
- Hide data complexity.
- Simplify commands for the user.
- Present the data in a different perspective from that of the base table.
- Store complex queries.
What is an Oracle sequence?
A sequence generates a serial list of unique numbers for numerical columns of a database's tables.
What is a synonym?
A synonym is an alias for a table, view, sequence or program unit.
What are the types of synonyms?
There are two types of synonyms private and public.
What is a private synonym?
Only its owner can access a private synonym.
What is a public synonym?
Any database user can access a public synonym.
What are synonyms used for?
- Mask the real name and owner of an object.
- Provide public access to an object
- Provide location transparency for tables, views or program units of a remote database.
- Simplify the SQL statements for database users.
What is an Oracle index?
An index is an optional structure associated with a table to have direct access to rows, which can be created to increase the performance of data retrieval. Index can be created on one or more columns of a table.
How are the index updates?
Indexes are automatically maintained and used by Oracle. Changes to table data are automatically incorporated into all relevant indexes.
What is a Tablespace?
A database is divided into Logical Storage Unit called tablespace. A tablespace is used to grouped related logical structures together
What is Rollback Segment ?
A Database contains one or more Rollback Segments to temporarily store "undo" information.
What are the Characteristics of Data Files ?
A data file can be associated with only one database. Once created a data file can't change size. One or more data files form a logical unit of database storage called a tablespace.
How to define Data Block size ?
A data block size is specified for each ORACLE database when the database is created. A database users and allocated free database space in ORACLE data blocks. Block size is specified in INIT.ORA file and can’t be changed latter.
What does a Control file Contain ?
A Control file records the physical structure of the database. It contains the following information.
Database Name
Names and locations of a database's files and redolog files.
Time stamp of database creation.
What is difference between UNIQUE constraint and PRIMARY KEY constraint ?
A column defined as UNIQUE can contain Nulls while a column defined as PRIMARY KEY can't contain Nulls.
What is Index Cluster ?
A Cluster with an index on the Cluster Key
When does a Transaction end ?
When it is committed or Rollbacked.
What is the effect of setting the value "ALL_ROWS" for OPTIMIZER_GOAL parameter of the ALTER SESSION command ? What are the factors that affect OPTIMIZER in choosing an Optimization approach ?
Answer The OPTIMIZER_MODE initialization parameter Statistics in the Data Dictionary the OPTIMIZER_GOAL parameter of the ALTER SESSION command hints in the statement.
What is the effect of setting the value "CHOOSE" for OPTIMIZER_GOAL, parameter of the ALTER SESSION Command ?
The Optimizer chooses Cost_based approach and optimizes with the goal of best throughput if statistics for atleast one of the tables accessed by the SQL statement exist in the data dictionary. Otherwise the OPTIMIZER chooses RULE_based approach.
How does one create a new database? (for DBA)
One can create and modify Oracle databases using the Oracle "dbca" (Database Configuration Assistant) utility. The dbca utility is located in the $ORACLE_HOME/bin directory. The Oracle Universal Installer (oui) normally starts it after installing the database server software.
One can also create databases manually using scripts. This option, however, is falling out of fashion, as it is quite involved and error prone. Look at this example for creating and Oracle 9i database:
CONNECT SYS AS SYSDBA
ALTER SYSTEM SET DB_CREATE_FILE_DEST='/u01/oradata/';
ALTER SYSTEM SET DB_CREATE_ONLINE_LOG_DEST_1='/u02/oradata/';
ALTER SYSTEM SET DB_CREATE_ONLINE_LOG_DEST_2='/u03/oradata/';
CREATE DATABASE;
What database block size should I use? (for DBA)
Oracle recommends that your database block size match, or be multiples of your operating system block size. One can use smaller block sizes, but the performance cost is significant. Your choice should depend on the type of application you are running. If you have many small transactions as with OLTP, use a smaller block size. With fewer but larger transactions, as with a DSS application, use a larger block size. If you are using a volume manager, consider your "operating system block size" to be 8K. This is because volume manager products use 8K blocks (and this is not configurable).
What are the different approaches used by Optimizer in choosing an execution plan ?
Rule-based and Cost-based.
What does ROLLBACK do ?
ROLLBACK retracts any of the changes resulting from the SQL statements in the transaction.
How does one coalesce free space ? (for DBA)
SMON coalesces free space (extents) into larger, contiguous extents every 2 hours and even then, only for a short period of time.
SMON will not coalesce free space if a tablespace's default storage parameter "pctincrease" is set to 0. With Oracle 7.3 one can manually coalesce a tablespace using the ALTER TABLESPACE ... COALESCE; command, until then use:
SQL> alter session set events 'immediate trace name coalesce level n';
Where 'n' is the tablespace number you get from SELECT TS#, NAME FROM SYS.TS$;
You can get status information about this process by selecting from the SYS.DBA_FREE_SPACE_COALESCED dictionary view.
How does one prevent tablespace fragmentation? (for DBA)
Always set PCTINCREASE to 0 or 100.
Bizarre values for PCTINCREASE will contribute to fragmentation. For example if you set PCTINCREASE to 1 you will see that your extents are going to have weird and wacky sizes: 100K, 100K, 101K, 102K, etc. Such extents of bizarre size are rarely re-used in their entirety. PCTINCREASE of 0 or 100 gives you nice round extent sizes that can easily be reused. E.g.. 100K, 100K, 200K, 400K, etc.
Use the same extent size for all the segments in a given tablespace. Locally Managed tablespaces (available from 8i onwards) with uniform extent sizes virtually eliminates any tablespace fragmentation. Note that the number of extents per segment does not cause any performance issue anymore, unless they run into thousands and thousands where additional I/O may be required to fetch the additional blocks where extent maps of the segment are stored.
Where can one find the high water mark for a table? (for DBA)
There is no single system table, which contains the high water mark (HWM) for a table. A table's HWM can be calculated using the results from the following SQL statements:
SELECT BLOCKS
FROM DBA_SEGMENTS
WHERE OWNER=UPPER(owner) AND SEGMENT_NAME = UPPER(table);
ANALYZE TABLE owner.table ESTIMATE STATISTICS;
SELECT EMPTY_BLOCKS
FROM DBA_TABLES
WHERE OWNER=UPPER(owner) AND SEGMENT_NAME = UPPER(table);
Thus, the tables' HWM = (query result 1) - (query result 2) - 1
NOTE: You can also use the DBMS_SPACE package and calculate the HWM = TOTAL_BLOCKS - UNUSED_BLOCKS - 1.
What is COST-based approach to optimization ?
Considering available access paths and determining the most efficient execution plan based on statistics in the data dictionary for the tables accessed by the statement and their associated clusters and indexes.
What does COMMIT do ?
COMMIT makes permanent the changes resulting from all SQL statements in the transaction. The changes made by the SQL statements of a transaction become visible to other user sessions transactions that start only after transaction is committed.
How are extents allocated to a segment? (for DBA)
Oracle8 and above rounds off extents to a multiple of 5 blocks when more than 5 blocks are requested. If one requests 16K or 2 blocks (assuming a 8K block size), Oracle doesn't round it up to 5 blocks, but it allocates 2 blocks or 16K as requested. If one asks for 8 blocks, Oracle will round it up to 10 blocks.
Space allocation also depends upon the size of contiguous free space available. If one asks for 8 blocks and Oracle finds a contiguous free space that is exactly 8 blocks, it would give it you. If it were 9 blocks, Oracle would also give it to you. Clearly Oracle doesn't always round extents to a multiple of 5 blocks.
The exception to this rule is locally managed tablespaces. If a tablespace is created with local extent management and the extent size is 64K, then Oracle allocates 64K or 8 blocks assuming 8K-block size. Oracle doesn't round it up to the multiple of 5 when a tablespace is locally managed.
Can one rename a database user (schema)? (for DBA)
No, this is listed as Enhancement Request 158508. Workaround:
Do a user-level export of user A
create new user B
Import system/manager fromuser=A touser=B
Drop user A
What are the components of physical database structure of Oracle database?
Oracle database is comprised of three types of files. One or more datafiles, two are more redo log files, and one or more control files.
What are the components of logical database structure of Oracle database?
There are tablespaces and database's schema objects.
What is a tablespace?
A database is divided into Logical Storage Unit called tablespaces. A tablespace is used to grouped related logical structures together.
What is SYSTEM tablespace and when is it created?
Every Oracle database contains a tablespace named SYSTEM, which is automatically created when the database is created. The SYSTEM tablespace always contains the data dictionary tables for the entire database.
Explain the relationship among database, tablespace and data file ?
Each databases logically divided into one or more tablespaces one or more data files are explicitly created for each tablespace.
What is schema?
A schema is collection of database objects of a user.
What are Schema Objects?
Schema objects are the logical structures that directly refer to the database's data. Schema objects include tables, views, sequences, synonyms, indexes, clusters, database triggers, procedures, functions packages and database links.
Can objects of the same schema reside in different tablespaces?
Yes.
Can a tablespace hold objects from different schemes?
Yes.
What is Oracle table?
A table is the basic unit of data storage in an Oracle database. The tables of a database hold all of the user accessible data. Table data is stored in rows and columns.
What is an Oracle view?
A view is a virtual table. Every view has a query attached to it. (The query is a SELECT statement that identifies the columns and rows of the table(s) the view uses.)
What is Partial Backup ?
A Partial Backup is any operating system backup short of a full backup, taken while the database is open or shut down.
What is Mirrored on-line Redo Log ?
A mirrored on-line redo log consists of copies of on-line redo log files physically located on separate disks, changes made to one member of the group are made to all members.
What is Full Backup ?
A full backup is an operating system backup of all data files, on-line redo log files and control file that constitute ORACLE database and the parameter.
Can a View based on another View ?
Yes.
Can a Tablespace hold objects from different Schemes ?
Yes.
Can objects of the same Schema reside in different tablespace ?
Yes.
What is the use of Control File ?
When an instance of an ORACLE database is started, its control file is used to identify the database and redo log files that must be opened for database operation to proceed. It is also used in database recovery.
Do View contain Data ?
Views do not contain or store data.
What are the Referential actions supported by FOREIGN KEY integrity constraint ?
UPDATE and DELETE Restrict - A referential integrity rule that disallows the update or deletion of referenced data. DELETE Cascade - When a referenced row is deleted all associated dependent rows are deleted.
What are the type of Synonyms?
There are two types of Synonyms Private and Public.
What is a Redo Log ?
The set of Redo Log files YSDATE,UID,USER or USERENV SQL functions, or the pseudo columns LEVEL or ROWNUM.
What is an Index Segment ?
Each Index has an Index segment that stores all of its data.
Explain the relationship among Database, Tablespace and Data file?
Each databases logically divided into one or more tablespaces one or more data files are explicitly created for each tablespace
What are the different type of Segments ?
Data Segment, Index Segment, Rollback Segment and Temporary Segment.
What are Clusters ?
Clusters are groups of one or more tables physically stores together to share common columns and are often used together.
What is an Integrity Constrains ?
An integrity constraint is a declarative way to define a business rule for a column of a table.
What is an Index ?
An Index is an optional structure associated with a table to have direct access to rows, which can be created to increase the performance of data retrieval. Index can be created on one or more columns of a table.
What is an Extent ?
An Extent is a specific number of contiguous data blocks, obtained in a single allocation, and used to store a specific type of information.
What is a View ?
A view is a virtual table. Every view has a Query attached to it. (The Query is a SELECT statement that identifies the columns and rows of the table(s) the view uses.)
What is Table ?
A table is the basic unit of data storage in an ORACLE database. The tables of a database hold all of the user accessible data. Table data is stored in rows and columns.
What are the advantages of views?
- Provide an additional level of table security, by restricting access to a predetermined set of rows and columns of a table.
- Hide data complexity.
- Simplify commands for the user.
- Present the data in a different perspective from that of the base table.
- Store complex queries.
What is an Oracle sequence?
A sequence generates a serial list of unique numbers for numerical columns of a database's tables.
What is a synonym?
A synonym is an alias for a table, view, sequence or program unit.
What are the types of synonyms?
There are two types of synonyms private and public.
What is a private synonym?
Only its owner can access a private synonym.
What is a public synonym?
Any database user can access a public synonym.
What are synonyms used for?
- Mask the real name and owner of an object.
- Provide public access to an object
- Provide location transparency for tables, views or program units of a remote database.
- Simplify the SQL statements for database users.
What is an Oracle index?
An index is an optional structure associated with a table to have direct access to rows, which can be created to increase the performance of data retrieval. Index can be created on one or more columns of a table.
How are the index updates?
Indexes are automatically maintained and used by Oracle. Changes to table data are automatically incorporated into all relevant indexes.
What is a Tablespace?
A database is divided into Logical Storage Unit called tablespace. A tablespace is used to grouped related logical structures together
What is Rollback Segment ?
A Database contains one or more Rollback Segments to temporarily store "undo" information.
What are the Characteristics of Data Files ?
A data file can be associated with only one database. Once created a data file can't change size. One or more data files form a logical unit of database storage called a tablespace.
How to define Data Block size ?
A data block size is specified for each ORACLE database when the database is created. A database users and allocated free database space in ORACLE data blocks. Block size is specified in INIT.ORA file and can’t be changed latter.
What does a Control file Contain ?
A Control file records the physical structure of the database. It contains the following information.
Database Name
Names and locations of a database's files and redolog files.
Time stamp of database creation.
What is difference between UNIQUE constraint and PRIMARY KEY constraint ?
A column defined as UNIQUE can contain Nulls while a column defined as PRIMARY KEY can't contain Nulls.
What is Index Cluster ?
A Cluster with an index on the Cluster Key
When does a Transaction end ?
When it is committed or Rollbacked.
What is the effect of setting the value "ALL_ROWS" for OPTIMIZER_GOAL parameter of the ALTER SESSION command ? What are the factors that affect OPTIMIZER in choosing an Optimization approach ?
Answer The OPTIMIZER_MODE initialization parameter Statistics in the Data Dictionary the OPTIMIZER_GOAL parameter of the ALTER SESSION command hints in the statement.
What is the effect of setting the value "CHOOSE" for OPTIMIZER_GOAL, parameter of the ALTER SESSION Command ?
The Optimizer chooses Cost_based approach and optimizes with the goal of best throughput if statistics for atleast one of the tables accessed by the SQL statement exist in the data dictionary. Otherwise the OPTIMIZER chooses RULE_based approach.
How does one create a new database? (for DBA)
One can create and modify Oracle databases using the Oracle "dbca" (Database Configuration Assistant) utility. The dbca utility is located in the $ORACLE_HOME/bin directory. The Oracle Universal Installer (oui) normally starts it after installing the database server software.
One can also create databases manually using scripts. This option, however, is falling out of fashion, as it is quite involved and error prone. Look at this example for creating and Oracle 9i database:
CONNECT SYS AS SYSDBA
ALTER SYSTEM SET DB_CREATE_FILE_DEST='/u01/oradata/';
ALTER SYSTEM SET DB_CREATE_ONLINE_LOG_DEST_1='/u02/oradata/';
ALTER SYSTEM SET DB_CREATE_ONLINE_LOG_DEST_2='/u03/oradata/';
CREATE DATABASE;
What database block size should I use? (for DBA)
Oracle recommends that your database block size match, or be multiples of your operating system block size. One can use smaller block sizes, but the performance cost is significant. Your choice should depend on the type of application you are running. If you have many small transactions as with OLTP, use a smaller block size. With fewer but larger transactions, as with a DSS application, use a larger block size. If you are using a volume manager, consider your "operating system block size" to be 8K. This is because volume manager products use 8K blocks (and this is not configurable).
What are the different approaches used by Optimizer in choosing an execution plan ?
Rule-based and Cost-based.
What does ROLLBACK do ?
ROLLBACK retracts any of the changes resulting from the SQL statements in the transaction.
How does one coalesce free space ? (for DBA)
SMON coalesces free space (extents) into larger, contiguous extents every 2 hours and even then, only for a short period of time.
SMON will not coalesce free space if a tablespace's default storage parameter "pctincrease" is set to 0. With Oracle 7.3 one can manually coalesce a tablespace using the ALTER TABLESPACE ... COALESCE; command, until then use:
SQL> alter session set events 'immediate trace name coalesce level n';
Where 'n' is the tablespace number you get from SELECT TS#, NAME FROM SYS.TS$;
You can get status information about this process by selecting from the SYS.DBA_FREE_SPACE_COALESCED dictionary view.
How does one prevent tablespace fragmentation? (for DBA)
Always set PCTINCREASE to 0 or 100.
Bizarre values for PCTINCREASE will contribute to fragmentation. For example if you set PCTINCREASE to 1 you will see that your extents are going to have weird and wacky sizes: 100K, 100K, 101K, 102K, etc. Such extents of bizarre size are rarely re-used in their entirety. PCTINCREASE of 0 or 100 gives you nice round extent sizes that can easily be reused. E.g.. 100K, 100K, 200K, 400K, etc.
Use the same extent size for all the segments in a given tablespace. Locally Managed tablespaces (available from 8i onwards) with uniform extent sizes virtually eliminates any tablespace fragmentation. Note that the number of extents per segment does not cause any performance issue anymore, unless they run into thousands and thousands where additional I/O may be required to fetch the additional blocks where extent maps of the segment are stored.
Where can one find the high water mark for a table? (for DBA)
There is no single system table, which contains the high water mark (HWM) for a table. A table's HWM can be calculated using the results from the following SQL statements:
SELECT BLOCKS
FROM DBA_SEGMENTS
WHERE OWNER=UPPER(owner) AND SEGMENT_NAME = UPPER(table);
ANALYZE TABLE owner.table ESTIMATE STATISTICS;
SELECT EMPTY_BLOCKS
FROM DBA_TABLES
WHERE OWNER=UPPER(owner) AND SEGMENT_NAME = UPPER(table);
Thus, the tables' HWM = (query result 1) - (query result 2) - 1
NOTE: You can also use the DBMS_SPACE package and calculate the HWM = TOTAL_BLOCKS - UNUSED_BLOCKS - 1.
What is COST-based approach to optimization ?
Considering available access paths and determining the most efficient execution plan based on statistics in the data dictionary for the tables accessed by the statement and their associated clusters and indexes.
What does COMMIT do ?
COMMIT makes permanent the changes resulting from all SQL statements in the transaction. The changes made by the SQL statements of a transaction become visible to other user sessions transactions that start only after transaction is committed.
How are extents allocated to a segment? (for DBA)
Oracle8 and above rounds off extents to a multiple of 5 blocks when more than 5 blocks are requested. If one requests 16K or 2 blocks (assuming a 8K block size), Oracle doesn't round it up to 5 blocks, but it allocates 2 blocks or 16K as requested. If one asks for 8 blocks, Oracle will round it up to 10 blocks.
Space allocation also depends upon the size of contiguous free space available. If one asks for 8 blocks and Oracle finds a contiguous free space that is exactly 8 blocks, it would give it you. If it were 9 blocks, Oracle would also give it to you. Clearly Oracle doesn't always round extents to a multiple of 5 blocks.
The exception to this rule is locally managed tablespaces. If a tablespace is created with local extent management and the extent size is 64K, then Oracle allocates 64K or 8 blocks assuming 8K-block size. Oracle doesn't round it up to the multiple of 5 when a tablespace is locally managed.
Can one rename a database user (schema)? (for DBA)
No, this is listed as Enhancement Request 158508. Workaround:
Do a user-level export of user A
create new user B
Import system/manager fromuser=A touser=B
Drop user A
C by dennis ritche and Kernighan ebbok download
C Programming by dennis ritche and Kernighan ebbok download
Download the ebook from following link Click Download
Download the ebook from following link Click Download
Open MVS(Multiple Virual storage) in Mainframes
Basic Information of Open MVS
“Mainframe environment”, which by default means “IBM Mainframe”, you need to have a basic idea of the IBM mainframe operating system. Today, it is know as MVS, which expands to Multiple Virtual Storage.
The MVS operating system has evolved over many years and has adapted to the changing technology and modern day requirements. Since the user base of MVS is very large, a change is not easy to Implement. The costs of the Mainframes are very high and the customer base is mostly made up of long-term customers with huge application and large databases to support. Most of these applications are also ‘Mission Critical’ applications. It is therefore imperative that any change to MVS also be backward compatible.
MVS is designed to work with many hundreds of users working together, located in the same locality or across continents. The MVS operating System was created by IBM and is said to ‘propriety’ OS. It has the capacity to supports a large number of peripherals like disks, tapes, printers, Network devices etc. The applications on these “Legacy systems” are typically where there is a huge amount of data and a large user base. Examples are Banking sector, Insurance Sector, Newspapers, Material & Inventory, Airlines, Credit Card System, Billing, Accounting, Shipping and others. Company’s that own these mainframes are typically those that are very big inherently or have to deal with vast amounts of data, which has to be processed fast.
“Mainframe environment”, which by default means “IBM Mainframe”, you need to have a basic idea of the IBM mainframe operating system. Today, it is know as MVS, which expands to Multiple Virtual Storage.
The MVS operating system has evolved over many years and has adapted to the changing technology and modern day requirements. Since the user base of MVS is very large, a change is not easy to Implement. The costs of the Mainframes are very high and the customer base is mostly made up of long-term customers with huge application and large databases to support. Most of these applications are also ‘Mission Critical’ applications. It is therefore imperative that any change to MVS also be backward compatible.
MVS is designed to work with many hundreds of users working together, located in the same locality or across continents. The MVS operating System was created by IBM and is said to ‘propriety’ OS. It has the capacity to supports a large number of peripherals like disks, tapes, printers, Network devices etc. The applications on these “Legacy systems” are typically where there is a huge amount of data and a large user base. Examples are Banking sector, Insurance Sector, Newspapers, Material & Inventory, Airlines, Credit Card System, Billing, Accounting, Shipping and others. Company’s that own these mainframes are typically those that are very big inherently or have to deal with vast amounts of data, which has to be processed fast.
Objectives and Advantages of CRM: CRM Interview
Objectives and Advantages of CRM: CRM Interview
Objectives of CRM:
Ø To create a consistent customer experience
Your relationship with customer should be thought of as an ongoing conversation without end.
Ø Collective consciousness expected
Customers talking to Accounts receivables person, sales person, call from telemarketing person, direct marketing, returning to web site.
Advantages of CRM:
Ø Provide better customer service
Ø Make call centers more efficient
Ø Cross sell products more effectively
Ø Help sales staff close deals faster
Ø Simplify marketing and sales processes
Ø Discover new customers
Ø Increase customer revenues
Objectives of CRM:
Ø To create a consistent customer experience
Your relationship with customer should be thought of as an ongoing conversation without end.
Ø Collective consciousness expected
Customers talking to Accounts receivables person, sales person, call from telemarketing person, direct marketing, returning to web site.
Advantages of CRM:
Ø Provide better customer service
Ø Make call centers more efficient
Ø Cross sell products more effectively
Ø Help sales staff close deals faster
Ø Simplify marketing and sales processes
Ø Discover new customers
Ø Increase customer revenues
Electronics,ECE Interview Questions
Electronics,ECE Interview Questions
1. Expand ECE.
Electronics & Communication Engineering.
2. What is Electronic?
The study and use of electrical devices that operate by controlling the flow of electrons or other electrically charged particles.
3. What is communication?
Communication means transferring a signal from the transmitter which passes through a medium then the output is obtained at the receiver. (or)communication says as transferring of message from one place to another place called communication.
4. Different types of communications? Explain.
Analog and digital communication.
As a technology, analog is the process of taking an audio or video signal (the human voice) and translating it into electronic pulses. Digital on the other hand is breaking the signal into a binary format where the audio or video data is represented by a series of "1"s and "0"s.
Digital signals are immune to noise, quality of transmission and reception is good, components used in digital communication can be produced with high precision and power consumption is also very less when compared with analog signals.
5. What is engineering?
The application of science to the needs of humanity and a profession in which a knowledge of the mathematical and natural sciences gained by study, experience, and practice is applied with judgment to develop ways to use economically the materials and forces of nature for the benefit of mankind.
6. Difference between electronic and electrical.
Electronics work on DC and with a voltage range of -48vDC to +48vDC. If the electronic device is plugged into a standard wall outlet, there will be a transformer inside which will convert the AC voltage you are supplying to the required DC voltage needed by the device. Examples: Computer, radio, T.V, etc...
Electric devices use line voltage (120vAC, 240vAC, etc...). Electric devices can also be designed to operate on DC sources, but will be at DC voltages above 48v. Examples: are incandescent lights, heaters, fridge, stove, etc...
7. What is sampling?
The process of obtaining a set of samples from a continuous function of time x(t) is referred to as sampling.
8. State sampling theorem.
It states that, while taking the samples of a continuous signal, it has to be taken care that the sampling rate is equal to or greater than twice the cut off frequency and the minimum sampling rate is known as the Nyquist rate.
9. What is cut-off frequency?
The frequency at which the response is -3dB with respect to the maximum response.
10. What is pass band?
Passband is the range of frequencies or wavelengths that can pass through a filter without being attenuated.
11. What is stop band?
A stopband is a band of frequencies, between specified limits, in which a circuit, such as a filter or telephone circuit, does not let signals through, or the attenuation is above the required stopband attenuation level.
12. Difference between mobile and a cell phone.
There is no difference, just language use, which differs from country to country, so in Britain it is called a mobile, and in USA and South Africa and other places a cell phone.
Even in Europe the name differs. The Germans call it a "handy", which in English has completely another meaning as an adjective, meaning useful.
In Italy it is called a telofonino or "little phone".
This difference in British and American English is also evident in many other things we use every day, like lifts and elevators, nappies and diapers, pickups and trucks. The list goes on and on, any student of English has to decide which he or she will use, as the default setting.
13. Explain RF?
Radio frequency (RF) is a frequency or rate of oscillation within the range of about 3 Hz to 300 GHz. This range corresponds to frequency of alternating current electrical signals used to produce and detect radio waves. Since most of this range is beyond the vibration rate that most mechanical systems can respond to, RF usually refers to oscillations in electrical circuits or electromagnetic radiation.
14. What is modulation? And where it is utilized?
Modulation is the process of varying some characteristic of a periodic wave with an external signals.
Radio communication superimposes this information bearing signal onto a carrier signal.
These high frequency carrier signals can be transmitted over the air easily and are capable of travelling long distances.
The characteristics (amplitude, frequency, or phase) of the carrier signal are varied in accordance with the information bearing signal.
Modulation is utilized to send an information bearing signal over long distances.
15. What is demodulation?
Demodulation is the act of removing the modulation from an analog signal to get the original baseband signal back. Demodulating is necessary because the receiver system receives a modulated signal with specific characteristics and it needs to turn it to base-band.
16. Name the modulation techniques.
For Analog modulation--AM, SSB, FM, PM and SM
Digital modulation--OOK, FSK, ASK, Psk, QAM, MSK, CPM, PPM, TCM, OFDM
17. Explain AM and FM.
AM-Amplitude modulation is a type of modulation where the amplitude of the carrier signal is varied in accordance with the information bearing signal.
FM-Frequency modulation is a type of modulation where the frequency of the carrier signal is varied in accordance with the information bearing signal.
18. Where do we use AM and FM?
AM is used for video signals for example TV. Ranges from 535 to 1705 kHz.
FM is used for audio signals for example Radio. Ranges from 88 to 108 MHz.
19. How does a mobile work?
When you talk into a mobile telephone it converts the sound of your voice to radiofrequency energy (radio waves). The radio waves are transmitted through the air to a nearby base station. The base station then sends the call through the telephone network until it reaches the person you are calling. When you receive a call on your mobile phone the message travels through the telephone network until it reaches a base station near to you. The base station sends out radio waves, which are detected by your telephone and converted back to speech. Depending on the equipment and the operator, the frequency that each operator utilises is 900MHz, 1800MHz or 2100MHz.
The mobile phone network operates on the basis of a series of cells. Each cell requires a radio base station to enable it to function.
There are three types of base station and each has a particular purpose:
1. The Macrocell is the largest type and provides the main coverage for mobile phone networks.
2. The Microcell is used to improve capacity in areas where demand to make calls is high, such as shopping centres.
3. The Picocell only has a range of a few hundred metres and may be used to boost weak signals within large buildings.
Each base station can only cope with a certain number of calls at any one time. So if demand exceeds the capacity of a base station an additional base station is needed.
20. What is a base station?
Base station is a radio receiver/transmitter that serves as the hub of the local wireless network, and may also be the gateway between a wired network and the wireless network.
21. How many satellites are required to cover the earth?
3 satellites are required to cover the entire earth, which is placed at 120 degree to each other. The life span of the satellite is about 15 years.
22. What is a repeater?
A repeater is an electronic device that receives a signal and retransmits it at a higher level and/or higher power, or onto the other side of an obstruction, so that the signal can cover longer distances without degradation.
23. What is attenuation?
Attenuation is the reduction in amplitude and intensity of a signal. Signals may attenuate exponentially by transmission through a medium, or by increments calculated in electronic circuitry or set by variable controls. Attenuation is an important property in telecommunications and ultrasound applications because of its importance in determining signal strength as a function of distance. Attenuation is usually measured in units of decibels per unit length of medium (dB/cm, dB/km, etc) and is represented by the attenuation coefficient of the medium in question.
24. What is multiplexing?
Multiplexing (known as muxing) is a term used to refer to a process where multiple analog message signals or digital data streams are combined into one signal over a shared medium. The aim is to share an expensive resource. For example, in telecommunications, several phone calls may be transferred using one wire.
25. What is CDMA, TDMA, FDMA?
Code division multiple access (CDMA) is a channel access method utilized by various radio communication technologies. CDMA employs spread-spectrum technology and a special coding scheme (where each transmitter is assigned a code) to allow multiple users to be multiplexed over the same physical channel. By contrast, time division multiple access (TDMA) divides access by time, while frequency-division multiple access (FDMA) divides it by frequency.
An analogy to the problem of multiple access is a room (channel) in which people wish to communicate with each other. To avoid confusion, people could take turns speaking (time division), speak at different pitches (frequency division), or speak in different directions (spatial division). In CDMA, they would speak different languages. People speaking the same language can understand each other, but not other people. Similarly, in radio CDMA, each group of users is given a shared code. Many codes occupy the same channel, but only users associated with a particular code can understand each other.
26. Difference between CDMA and GSM.
These are the two different means of mobile communication being presently used worldwide. The basic difference lies in the Multiplexing method used in the aerial communication i.e. from Mobile Tower to your mobile and vice versa.
CDMA uses Code Division Multiple Access as the name itself indicates, for example you are in a hall occupied with number of people speaking different language. You will find that the one language you know will be heard by you and the others will be treated like noise. In the same manner each CDMA mobile communication takes place with a "code" communicating between them and the other end if one is knowing that code then only it can listen to the data being transmitted i.e. the communication is in the coded form.
On the other hand GSM (Global System for Mobile Communications) uses narrowband TDMA, which allows eight simultaneous calls on the same radio frequency. TDMA works by dividing a radio frequency into time slots and then allocating slots to multiple calls. In this way, a single frequency can support multiple, simultaneous data channels.
27. What is an Amplifier?
An electronic device or electrical circuit that is used to boost (amplify) the power, voltage or current of an applied signal.
28. What is Barkhausen criteria?
Barkhausen criteria, without which you will not know which conditions, are to be satisfied for oscillations.
“Oscillations will not be sustained if, at the oscillator frequency, the magnitude of the product of the transfer gain of the amplifier and the magnitude of the feedback factor of the feedback network ( the magnitude of the loop gain ) are less than unity”.
The condition of unity loop gain -Aβ = 1 is called the Barkhausen criterion. This condition implies that
Aβ
= 1and that the phase of - Aβ is zero.
29. Explain Full duplex and half duplex.
Full duplex refers to the transmission of data in two directions simultaneously. For example, a telephone is a full-duplex device because both parties can talk at once. In contrast, a walkie-talkie is a half-duplex device because only one party can transmit at a time.
Most modems have a switch that lets you choose between full-duplex and half-duplex modes. The choice depends on which communications program you are running.
In full-duplex mode, data you transmit does not appear on your screen until it has been received and sent back by the other party. This enables you to validate that the data has been accurately transmitted. If your display screen shows two of each character, it probably means that your modem is set to half-duplex mode when it should be in full-duplex mode.
30. What is a feedback? And explain different types of feedback.
Feedback is a process whereby some proportion of the output signal of a system is passed (fed back) to the input. This is often used to control the dynamic behaviour of the system.
Types of feedback:
Negative feedback: This tends to reduce output (but in amplifiers, stabilizes and linearizes operation). Negative feedback feeds part of a system's output, inverted, into the system's input; generally with the result that fluctuations are attenuated.
Positive feedback: This tends to increase output. Positive feedback, sometimes referred to as "cumulative causation", is a feedback loop system in which the system responds to perturbation (A perturbation means a system, is an alteration of function, induced by external or internal mechanisms) in the same direction as the perturbation. In contrast, a system that responds to the perturbation in the opposite direction is called a negative feedback system.
Bipolar feedback: which can either increase or decrease output.
31. Advantages of negative feedback over positive feedback.
Much attention has been given by researchers to negative feedback processes, because negative feedback processes lead systems towards equilibrium states. Positive feedback reinforces a given tendency of a system and can lead a system away from equilibrium states, possibly causing quite unexpected results.
32. Example for negative feedback and positive feedback.
Example for –ve feedback is ---Amplifiers
And for +ve feedback is – Oscillators
33. What is Oscillator?
An oscillator is a circuit that creates a waveform output from a direct current input. The two main types of oscillator are harmonic and relaxation. The harmonic oscillators have smooth curved waveforms, while relaxation oscillators have waveforms with sharp changes.
34. What is a transducer and transponder?
A transducer is a device, usually electrical, electronic, electro-mechanical, electromagnetic, photonic, or photovoltaic that converts one type of energy or physical attribute to another for various purposes including measurement or information transfer.
In telecommunication, the term transponder (short-for Transmitter-responder and sometimes abbreviated to XPDR, XPNDR, TPDR or TP) has the following meanings:
* An automatic device that receives, amplifies, and retransmits a signal on a different frequency (see also broadcast translator).
* An automatic device that transmits a predetermined message in response to a predefined received signal.
* A receiver-transmitter that will generate a reply signal upon proper electronic interrogation.
A communications satellite’s channels are called transponders, because each is a separate transceiver or repeater.
35. What is an Integrated Circuit?
An integrated circuit (IC), also called a microchip, is an electronic circuit etched onto a silicon chip. Their main advantages are low cost, low power, high performance, and very small size.
36. What is crosstalk?
Crosstalk is a form of interference caused by signals in nearby conductors. The most common example is hearing an unwanted conversation on the telephone. Crosstalk can also occur in radios, televisions, networking equipment, and even electric guitars.
37. What is a rectifier?
A rectifier changes alternating current into direct current. This process is called rectification. The three main types of rectifier are the half-wave, full-wave, and bridge. A rectifier is the opposite of an inverter, which changes direct current into alternating current.
HWR- The simplest type is the half-wave rectifier, which can be made with just one diode. When the voltage of the alternating current is positive, the diode becomes forward-biased and current flows through it. When the voltage is negative, the diode is reverse-biased and the current stops. The result is a clipped copy of the alternating current waveform with only positive voltage, and an average voltage that is one third of the peak input voltage. This pulsating direct current is adequate for some components, but others require a more steady current. This requires a full-wave rectifier that can convert both parts of the cycle to positive voltage.
FWR- The full-wave rectifier is essentially two half-wave rectifiers, and can be made with two diodes and an earthed centre tap on the transformer. The positive voltage half of the cycle flows through one diode, and the negative half flows through the other. The centre tap allows the circuit to be completed because current cannot flow through the other diode. The result is still a pulsating direct current but with just over half the input peak voltage, and double the frequency.
38. What is resistor?
A resistor is a two-terminal electronic component that opposes an electric current by producing a voltage drop between its terminals in proportion to the current, that is, in accordance with Ohm's law: V = IR.
39. What is capacitor?
A capacitor is an electrical/electronic device that can store energy in the electric field between a pair of conductors (called "plates"). The process of storing energy in the capacitor is known as "charging", and involves electric charges of equal magnitude, but opposite polarity, building up on each plate.
Capacitors are often used in electric and electronic circuits as energy-storage devices. They can also be used to differentiate between high-frequency and low-frequency signals. This property makes them useful in electronic filters.
Capacitors are occasionally referred to as condensers. This term is considered archaic in English, but most other languages use a cognate of condenser to refer to a capacitor.
40. What is inductor?
An inductor is a passive electrical device employed in electrical circuits for its property of inductance. An inductor can take many forms.
41. What is conductor?
A substance, body, or device that readily conducts heat, electricity, sound, etc. Copper is a good conductor of electricity.
42. What is a semi conductor?
A semiconductor is a solid material that has electrical conductivity in between that of a conductor and that of an insulator(An Insulator is a material that resists the flow of electric current. It is an object intended to support or separate electrical conductors without passing current through itself); it can vary over that wide range either permanently or dynamically.
43. What is diode?
In electronics, a diode is a two-terminal device. Diodes have two active electrodes between which the signal of interest may flow, and most are used for their unidirectional current property.
44. What is transistor?
In electronics, a transistor is a semiconductor device commonly used to amplify or switch electronic signals. The transistor is the fundamental building block of computers, and all other modern electronic devices. Some transistors are packaged individually but most are found in integrated circuits.
45. What is op-amp?
An operational amplifier, often called an op-amp , is a DC-coupled high-gain electronic voltage amplifier with differential inputs[1] and, usually, a single output. Typically the output of the op-amp is controlled either by negative feedback, which largely determines the magnitude of its output voltage gain, or by positive feedback, which facilitates regenerative gain and oscillation.
1. Expand ECE.
Electronics & Communication Engineering.
2. What is Electronic?
The study and use of electrical devices that operate by controlling the flow of electrons or other electrically charged particles.
3. What is communication?
Communication means transferring a signal from the transmitter which passes through a medium then the output is obtained at the receiver. (or)communication says as transferring of message from one place to another place called communication.
4. Different types of communications? Explain.
Analog and digital communication.
As a technology, analog is the process of taking an audio or video signal (the human voice) and translating it into electronic pulses. Digital on the other hand is breaking the signal into a binary format where the audio or video data is represented by a series of "1"s and "0"s.
Digital signals are immune to noise, quality of transmission and reception is good, components used in digital communication can be produced with high precision and power consumption is also very less when compared with analog signals.
5. What is engineering?
The application of science to the needs of humanity and a profession in which a knowledge of the mathematical and natural sciences gained by study, experience, and practice is applied with judgment to develop ways to use economically the materials and forces of nature for the benefit of mankind.
6. Difference between electronic and electrical.
Electronics work on DC and with a voltage range of -48vDC to +48vDC. If the electronic device is plugged into a standard wall outlet, there will be a transformer inside which will convert the AC voltage you are supplying to the required DC voltage needed by the device. Examples: Computer, radio, T.V, etc...
Electric devices use line voltage (120vAC, 240vAC, etc...). Electric devices can also be designed to operate on DC sources, but will be at DC voltages above 48v. Examples: are incandescent lights, heaters, fridge, stove, etc...
7. What is sampling?
The process of obtaining a set of samples from a continuous function of time x(t) is referred to as sampling.
8. State sampling theorem.
It states that, while taking the samples of a continuous signal, it has to be taken care that the sampling rate is equal to or greater than twice the cut off frequency and the minimum sampling rate is known as the Nyquist rate.
9. What is cut-off frequency?
The frequency at which the response is -3dB with respect to the maximum response.
10. What is pass band?
Passband is the range of frequencies or wavelengths that can pass through a filter without being attenuated.
11. What is stop band?
A stopband is a band of frequencies, between specified limits, in which a circuit, such as a filter or telephone circuit, does not let signals through, or the attenuation is above the required stopband attenuation level.
12. Difference between mobile and a cell phone.
There is no difference, just language use, which differs from country to country, so in Britain it is called a mobile, and in USA and South Africa and other places a cell phone.
Even in Europe the name differs. The Germans call it a "handy", which in English has completely another meaning as an adjective, meaning useful.
In Italy it is called a telofonino or "little phone".
This difference in British and American English is also evident in many other things we use every day, like lifts and elevators, nappies and diapers, pickups and trucks. The list goes on and on, any student of English has to decide which he or she will use, as the default setting.
13. Explain RF?
Radio frequency (RF) is a frequency or rate of oscillation within the range of about 3 Hz to 300 GHz. This range corresponds to frequency of alternating current electrical signals used to produce and detect radio waves. Since most of this range is beyond the vibration rate that most mechanical systems can respond to, RF usually refers to oscillations in electrical circuits or electromagnetic radiation.
14. What is modulation? And where it is utilized?
Modulation is the process of varying some characteristic of a periodic wave with an external signals.
Radio communication superimposes this information bearing signal onto a carrier signal.
These high frequency carrier signals can be transmitted over the air easily and are capable of travelling long distances.
The characteristics (amplitude, frequency, or phase) of the carrier signal are varied in accordance with the information bearing signal.
Modulation is utilized to send an information bearing signal over long distances.
15. What is demodulation?
Demodulation is the act of removing the modulation from an analog signal to get the original baseband signal back. Demodulating is necessary because the receiver system receives a modulated signal with specific characteristics and it needs to turn it to base-band.
16. Name the modulation techniques.
For Analog modulation--AM, SSB, FM, PM and SM
Digital modulation--OOK, FSK, ASK, Psk, QAM, MSK, CPM, PPM, TCM, OFDM
17. Explain AM and FM.
AM-Amplitude modulation is a type of modulation where the amplitude of the carrier signal is varied in accordance with the information bearing signal.
FM-Frequency modulation is a type of modulation where the frequency of the carrier signal is varied in accordance with the information bearing signal.
18. Where do we use AM and FM?
AM is used for video signals for example TV. Ranges from 535 to 1705 kHz.
FM is used for audio signals for example Radio. Ranges from 88 to 108 MHz.
19. How does a mobile work?
When you talk into a mobile telephone it converts the sound of your voice to radiofrequency energy (radio waves). The radio waves are transmitted through the air to a nearby base station. The base station then sends the call through the telephone network until it reaches the person you are calling. When you receive a call on your mobile phone the message travels through the telephone network until it reaches a base station near to you. The base station sends out radio waves, which are detected by your telephone and converted back to speech. Depending on the equipment and the operator, the frequency that each operator utilises is 900MHz, 1800MHz or 2100MHz.
The mobile phone network operates on the basis of a series of cells. Each cell requires a radio base station to enable it to function.
There are three types of base station and each has a particular purpose:
1. The Macrocell is the largest type and provides the main coverage for mobile phone networks.
2. The Microcell is used to improve capacity in areas where demand to make calls is high, such as shopping centres.
3. The Picocell only has a range of a few hundred metres and may be used to boost weak signals within large buildings.
Each base station can only cope with a certain number of calls at any one time. So if demand exceeds the capacity of a base station an additional base station is needed.
20. What is a base station?
Base station is a radio receiver/transmitter that serves as the hub of the local wireless network, and may also be the gateway between a wired network and the wireless network.
21. How many satellites are required to cover the earth?
3 satellites are required to cover the entire earth, which is placed at 120 degree to each other. The life span of the satellite is about 15 years.
22. What is a repeater?
A repeater is an electronic device that receives a signal and retransmits it at a higher level and/or higher power, or onto the other side of an obstruction, so that the signal can cover longer distances without degradation.
23. What is attenuation?
Attenuation is the reduction in amplitude and intensity of a signal. Signals may attenuate exponentially by transmission through a medium, or by increments calculated in electronic circuitry or set by variable controls. Attenuation is an important property in telecommunications and ultrasound applications because of its importance in determining signal strength as a function of distance. Attenuation is usually measured in units of decibels per unit length of medium (dB/cm, dB/km, etc) and is represented by the attenuation coefficient of the medium in question.
24. What is multiplexing?
Multiplexing (known as muxing) is a term used to refer to a process where multiple analog message signals or digital data streams are combined into one signal over a shared medium. The aim is to share an expensive resource. For example, in telecommunications, several phone calls may be transferred using one wire.
25. What is CDMA, TDMA, FDMA?
Code division multiple access (CDMA) is a channel access method utilized by various radio communication technologies. CDMA employs spread-spectrum technology and a special coding scheme (where each transmitter is assigned a code) to allow multiple users to be multiplexed over the same physical channel. By contrast, time division multiple access (TDMA) divides access by time, while frequency-division multiple access (FDMA) divides it by frequency.
An analogy to the problem of multiple access is a room (channel) in which people wish to communicate with each other. To avoid confusion, people could take turns speaking (time division), speak at different pitches (frequency division), or speak in different directions (spatial division). In CDMA, they would speak different languages. People speaking the same language can understand each other, but not other people. Similarly, in radio CDMA, each group of users is given a shared code. Many codes occupy the same channel, but only users associated with a particular code can understand each other.
26. Difference between CDMA and GSM.
These are the two different means of mobile communication being presently used worldwide. The basic difference lies in the Multiplexing method used in the aerial communication i.e. from Mobile Tower to your mobile and vice versa.
CDMA uses Code Division Multiple Access as the name itself indicates, for example you are in a hall occupied with number of people speaking different language. You will find that the one language you know will be heard by you and the others will be treated like noise. In the same manner each CDMA mobile communication takes place with a "code" communicating between them and the other end if one is knowing that code then only it can listen to the data being transmitted i.e. the communication is in the coded form.
On the other hand GSM (Global System for Mobile Communications) uses narrowband TDMA, which allows eight simultaneous calls on the same radio frequency. TDMA works by dividing a radio frequency into time slots and then allocating slots to multiple calls. In this way, a single frequency can support multiple, simultaneous data channels.
27. What is an Amplifier?
An electronic device or electrical circuit that is used to boost (amplify) the power, voltage or current of an applied signal.
28. What is Barkhausen criteria?
Barkhausen criteria, without which you will not know which conditions, are to be satisfied for oscillations.
“Oscillations will not be sustained if, at the oscillator frequency, the magnitude of the product of the transfer gain of the amplifier and the magnitude of the feedback factor of the feedback network ( the magnitude of the loop gain ) are less than unity”.
The condition of unity loop gain -Aβ = 1 is called the Barkhausen criterion. This condition implies that
Aβ
= 1and that the phase of - Aβ is zero.
29. Explain Full duplex and half duplex.
Full duplex refers to the transmission of data in two directions simultaneously. For example, a telephone is a full-duplex device because both parties can talk at once. In contrast, a walkie-talkie is a half-duplex device because only one party can transmit at a time.
Most modems have a switch that lets you choose between full-duplex and half-duplex modes. The choice depends on which communications program you are running.
In full-duplex mode, data you transmit does not appear on your screen until it has been received and sent back by the other party. This enables you to validate that the data has been accurately transmitted. If your display screen shows two of each character, it probably means that your modem is set to half-duplex mode when it should be in full-duplex mode.
30. What is a feedback? And explain different types of feedback.
Feedback is a process whereby some proportion of the output signal of a system is passed (fed back) to the input. This is often used to control the dynamic behaviour of the system.
Types of feedback:
Negative feedback: This tends to reduce output (but in amplifiers, stabilizes and linearizes operation). Negative feedback feeds part of a system's output, inverted, into the system's input; generally with the result that fluctuations are attenuated.
Positive feedback: This tends to increase output. Positive feedback, sometimes referred to as "cumulative causation", is a feedback loop system in which the system responds to perturbation (A perturbation means a system, is an alteration of function, induced by external or internal mechanisms) in the same direction as the perturbation. In contrast, a system that responds to the perturbation in the opposite direction is called a negative feedback system.
Bipolar feedback: which can either increase or decrease output.
31. Advantages of negative feedback over positive feedback.
Much attention has been given by researchers to negative feedback processes, because negative feedback processes lead systems towards equilibrium states. Positive feedback reinforces a given tendency of a system and can lead a system away from equilibrium states, possibly causing quite unexpected results.
32. Example for negative feedback and positive feedback.
Example for –ve feedback is ---Amplifiers
And for +ve feedback is – Oscillators
33. What is Oscillator?
An oscillator is a circuit that creates a waveform output from a direct current input. The two main types of oscillator are harmonic and relaxation. The harmonic oscillators have smooth curved waveforms, while relaxation oscillators have waveforms with sharp changes.
34. What is a transducer and transponder?
A transducer is a device, usually electrical, electronic, electro-mechanical, electromagnetic, photonic, or photovoltaic that converts one type of energy or physical attribute to another for various purposes including measurement or information transfer.
In telecommunication, the term transponder (short-for Transmitter-responder and sometimes abbreviated to XPDR, XPNDR, TPDR or TP) has the following meanings:
* An automatic device that receives, amplifies, and retransmits a signal on a different frequency (see also broadcast translator).
* An automatic device that transmits a predetermined message in response to a predefined received signal.
* A receiver-transmitter that will generate a reply signal upon proper electronic interrogation.
A communications satellite’s channels are called transponders, because each is a separate transceiver or repeater.
35. What is an Integrated Circuit?
An integrated circuit (IC), also called a microchip, is an electronic circuit etched onto a silicon chip. Their main advantages are low cost, low power, high performance, and very small size.
36. What is crosstalk?
Crosstalk is a form of interference caused by signals in nearby conductors. The most common example is hearing an unwanted conversation on the telephone. Crosstalk can also occur in radios, televisions, networking equipment, and even electric guitars.
37. What is a rectifier?
A rectifier changes alternating current into direct current. This process is called rectification. The three main types of rectifier are the half-wave, full-wave, and bridge. A rectifier is the opposite of an inverter, which changes direct current into alternating current.
HWR- The simplest type is the half-wave rectifier, which can be made with just one diode. When the voltage of the alternating current is positive, the diode becomes forward-biased and current flows through it. When the voltage is negative, the diode is reverse-biased and the current stops. The result is a clipped copy of the alternating current waveform with only positive voltage, and an average voltage that is one third of the peak input voltage. This pulsating direct current is adequate for some components, but others require a more steady current. This requires a full-wave rectifier that can convert both parts of the cycle to positive voltage.
FWR- The full-wave rectifier is essentially two half-wave rectifiers, and can be made with two diodes and an earthed centre tap on the transformer. The positive voltage half of the cycle flows through one diode, and the negative half flows through the other. The centre tap allows the circuit to be completed because current cannot flow through the other diode. The result is still a pulsating direct current but with just over half the input peak voltage, and double the frequency.
38. What is resistor?
A resistor is a two-terminal electronic component that opposes an electric current by producing a voltage drop between its terminals in proportion to the current, that is, in accordance with Ohm's law: V = IR.
39. What is capacitor?
A capacitor is an electrical/electronic device that can store energy in the electric field between a pair of conductors (called "plates"). The process of storing energy in the capacitor is known as "charging", and involves electric charges of equal magnitude, but opposite polarity, building up on each plate.
Capacitors are often used in electric and electronic circuits as energy-storage devices. They can also be used to differentiate between high-frequency and low-frequency signals. This property makes them useful in electronic filters.
Capacitors are occasionally referred to as condensers. This term is considered archaic in English, but most other languages use a cognate of condenser to refer to a capacitor.
40. What is inductor?
An inductor is a passive electrical device employed in electrical circuits for its property of inductance. An inductor can take many forms.
41. What is conductor?
A substance, body, or device that readily conducts heat, electricity, sound, etc. Copper is a good conductor of electricity.
42. What is a semi conductor?
A semiconductor is a solid material that has electrical conductivity in between that of a conductor and that of an insulator(An Insulator is a material that resists the flow of electric current. It is an object intended to support or separate electrical conductors without passing current through itself); it can vary over that wide range either permanently or dynamically.
43. What is diode?
In electronics, a diode is a two-terminal device. Diodes have two active electrodes between which the signal of interest may flow, and most are used for their unidirectional current property.
44. What is transistor?
In electronics, a transistor is a semiconductor device commonly used to amplify or switch electronic signals. The transistor is the fundamental building block of computers, and all other modern electronic devices. Some transistors are packaged individually but most are found in integrated circuits.
45. What is op-amp?
An operational amplifier, often called an op-amp , is a DC-coupled high-gain electronic voltage amplifier with differential inputs[1] and, usually, a single output. Typically the output of the op-amp is controlled either by negative feedback, which largely determines the magnitude of its output voltage gain, or by positive feedback, which facilitates regenerative gain and oscillation.
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