Interview Questions

Joins are used to combine data of one or more tables. Joins should be used when there is abundant data. Joins can be LEFT, RIGHT, OUTER, INNER or even SELF JOIN. The purpose is to bind data from multiple tables without any receptivity

Web browser is a software application used to locate,retrieve and display content on the World Wide Web, including Web pages, images, videos and other files.

Examples : Microsoft Internet Expiorer , Mozilla Firefox , Google Chrome, Opers , Safari etc...

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 and all methods are implicitly abstract. An interface has all public members and no implementation. An abstract class is a class which may have the usual flavors of class members (private, protected, etc.), but has some abstract methods.

Oracle NOT NULL is used on a column to ensure that the value for that column can never be NULL.
Example:
Below, the constraint is that the id should never be NULL. If it is, oracle throws an error.
create table employee ( id number NOT NULL, Name varchar(200) );

Comments are Non Executable statements in program & Explain program logic.

=> When a consumer wants to buy a certain product, he go to the website and selects the product he wants to buy. 

=> Once the product is selected, the consumer transaction is moved to the online transaction server where he places an order. 

=> The informations is exchanged over a secure channel through a private gateway to a processing network. 

=> The networked banks accept or reject the transaction.

 All this happens in just a matter of seconds. E-commerce is a very secure due to the SSL (Secure Socket Layer) technology.

A NSArray’s contents can not be modified once it’s been created whereas a NSMutableArray can be modified as needed, i.e items can be added/removed from it.