What is a cascading update?

Referential integrity constraints require that foreign key value in one table correspond to primary key values in another. If the value of the primary key is changed, that is, updated, the value of the foreign key must immediately be changed to match it. Cascading updates will set this change to be done automatically by the DBMS whenever necessary

What is PL/SQL?

PL/SQL is Oracle's Procedural Language extension to SQL. The language includes object oriented programming techniques such as encapsulation, function overloading, information hiding (all but inheritance), and so, brings state-of-the-art programming to the Oracle database server and a variety of Oracle tools

What is a Candidate Key?

A table may have more than one combination of columns that could uniquely identify the rows in a table, each combination is a Candidate Key

Difference betwween UNION and UNION ALL

UNION will remove the duplicate rows from the result set while UNION ALL does not.

Difference between TRUNCATE and DELETE

• Both result in deleting of the rows in the table
• TRUNCATE call cannot be rolled back  and all memory space for that table is released back to the server while DELETE call can be rolled back
• TRUNCATE call is DDL command while DELETE call is DML command
• TRUNCATE call is faster than DELETE call

Difference between value types and reference types.

Following are the differences between value types and reference types in C#:

• Value types are stored on the stack where as reference types are stored on the managed heap
• Value type variables directly contain their values where as reference variables holds only a reference to the location of the object that is created on the managed heap
• There is no heap allocation or garbage collection overhead for value-type variables. As reference types are stored on the managed heap, they have the over head of object allocation and garbage collection
• Value types cannot inherit from another class or struct. Value types can only inherit from interfaces. Reference types can inherit from another class or interface 

Types of comments

There are three types of comments in c#:

1. Single line(//)

//This is a single line comment

2. Multi line(/*   */)

/*  This is a 

multi line comment */

3. Page/XML(///)

/// This is an XML comment

What are the types of Authentication?

There are three types of Authentication:

1. Windows Authentication: uses the security features integrated into the Windows NT and Windows XP operating system to authenticate and authorize web application users
2. Forms Authentication: allows you to create your own list/database of users and validate the identity of those users when they visit your web site
3. Passport Authentication: uses the Microsoft centralized authentication provider to identify users. Passport provides a way to for users to use a single identity across multiple web applications. To use Passport Authentication in your Web application, you must install the Passport SDK

For what purpose Global.asax file used?

It executes application-level events and sets application-level variables.

What is garbage collection?

It is a system where a run-time component takes responsibility for managing the lifetime of objects and the heap memory that they occupy.