SQL Tutorials Point | Interview Q&A

What is Constructors?

A constructor is a member function in a class that has the same name as its class. The constructor is automatically invoked whenever an object class is created. It constructs the values of data members while initializing the class.

What is an object?

An object is an instance of a class through which we access the methods of that class. "New" keyword is used to create an object. A class that creates an object in memory will contain the information about the methods, variables and behavior of that class.

What is the difference between ExecuteScalar and ExecuteNonQuery?

ExecuteScalar returns output value where as ExecuteNonQuery does not return any value but the number of rows affected by the query. ExecuteScalar used for fetching a single value and ExecuteNonQuery used to execute Insert and Update statements.

How we can force all the validation controls to run?

The Page.Validate() method is used to force all the validation controls to run and to perform validation.

What is the difference between public, static and void?

Public: Public declared variables or methods are accessible anywhere in the application. Static declared variables or methods are globally accessible without creating an instance of the class.

Static: Static member are by default not globally accessible it depends upon the type of access modified used. The compiler stores the address of the method as the entry point and uses this information to begin execution before any objects are created.

Void: Void is a type modifier that states that the method or variable does not return any value.

Can multiple catch blocks be executed?

No, Multiple catch blocks can't be executed. Once the proper catch code executed, the control is transferred to the finally block and then the code that follows the finally block gets executed.

what is boxing and unboxing?

Boxing is assigning a value type to reference type variable.

Unboxing is reverse of boxing ie. Assigning reference type variable to value type variable.

What is RedirectPermanent in ASP.Net?

RedirectPermanent Performs a permanent redirection from the requested URL to the specified URL. Once the redirection is done, it also returns 301 Moved Permanently responses.

What is Cross Page Posting?

When we click submit button on a web page, the page post the data to the same page. The technique in which we post the data to different pages is called Cross Page posting. This can be achieved by setting POSTBACKURL property of the button that causes the postback. Findcontrol method of PreviousPage can be used to get the posted values on the page to which the page has been posted.

What are the different types of caching?

ASP.NET has 3 Type of caching :

Output Caching,
Fragment Caching,
Data Caching.