Dot net Interview Question and Answers

Difference between Session and Cookies

noreply@blogger.com (Venkat) — Sat, 04 May 2013 07:07:00 +0000

Sessions

It is used to store user information in server memory. Usually it stores userid, name etc.. sensitive information stored in session and it will maintain its state when you navigate through a website. You can store the session information either in cookies or cookieless mode.

If cookieless = false, session value stored in cookies, if it true it will be stored in the browser URL. but if you copy the URL and paste in another tab of the same browser the session will be expired.

You can store the session in three modes

In-Proc

State server

SQL server

Example

Session["userName"] = "Ganesh Ram";

if(Session["UserName"] != null)
  lblUserName.Text = Session["UserName"].ToString();

Cookies

Cookies are stored per-user on the users machine. A cookie is usually just a bit of information. Cookies are usually used for simple user settings colours preferences etc. No sensitive information should ever be stored in a cookie.

You can never fully trust that a cookie has not been tampered with by a user or outside source however if security is a big concern and you must use cookies then you can either encrypt your cookies or set them to only be transmitted over SSL. A user can clear there cookies at any time or not allow cookies altogether so you cannot count on them being there just because I user has visited your site in the past.

//add a username Cookie
Response.Cookies["UserName"].Value = "Ganesh Ram";
Response.Cookies["UserName"].Expires = DateTime.Now.AddDays(10);

//request a username cookie
if(Request.Cookies["UserName"] != null)
   lblUserName.Text = Server.HtmlEncode(Request.Cookies["UserName"].Value);

Difference between Clustered index and Non-Clustered index

noreply@blogger.com (Venkat) — Sat, 04 May 2013 06:39:00 +0000

Indexing is way to sort and search records in the table. It will improve the speed of locating and retrieval of records from the table

In SQL there are two types of index.

1. Clustered index

2. Non-Clustered index.

Clustered index is unique for any given table and we can have only one clustered index on a table. The leaf level of a clustered index is the actual data and the data is resorted in case of clustered index.

Whereas in case of non-clustered index the leaf level is actually a pointer to the data in rows so we can have as many non-clustered indexes as we can on the db

In SQL 2005

Clustered index - 1 Clustered index

Non-Clustered index - 249 Non-Clustered index

In SQL 2008

Clustered index - 1 Clustered index

Non-Clustered index - 999 Non-Clustered index

Example
USE Sample
GO
CREATE TABLE Employee
(ID bigint PRIMARY KEY CLUSTERED,
Name nvarchar(150),
Address nvarchar(250),
Salary varchar(25) )
GO
CREATE NONCLUSTERED INDEX EmpName ON Employee(Name)
GO

Define Stored procedure ?

noreply@blogger.com (Venkat) — Thu, 21 Oct 2010 17:58:00 +0000

It is a collection of transact sql statements that can take or return user supplied parameters.

Maximum size of stored procedure is 128 MB.

Difference between Having and Group By clause ?

noreply@blogger.com (Venkat) — Thu, 21 Oct 2010 17:57:00 +0000

Having Clause : To filter the rows from the grouped results

Group By : is used for grouping the operation.

Group by : Ccause is used to group the output of the WHERE clause..

Define View ?

noreply@blogger.com (Venkat) — Thu, 21 Oct 2010 17:56:00 +0000

It is nothing but a virtual table that represent the data in one or more tables in a alternative way.

What is index ?

noreply@blogger.com (Venkat) — Thu, 21 Oct 2010 17:55:00 +0000

Index is a pointer in sql server to retrieve the data faster from database.

It’s a physical structure containing pointers to data.

Its created in existing tables to locate rows more quickly and efficiently.

Types of Index:

a) Clustered Index : It contains only one index ie: Creating a primary key for the table.
Physical sorting of data in the storage media.

b) Non-Clustered Index : A table can contains 249 non-clustered index, It can be created outside of the database tables , that contain a sorted list of references to the table itself.

Define Delegates ?

noreply@blogger.com (Venkat) — Thu, 21 Oct 2010 17:54:00 +0000

Delegate is a class that can hold reference to a method or a function .

Delegate class has a signature and it only reference those method whose signature is compliant with the class.

Delegates are type safe , secure , object oriented.

Difference b/w int.Parse and Convert.ToInt32()?

noreply@blogger.com (Venkat) — Thu, 21 Oct 2010 17:54:00 +0000

Int.Parse – It can’t handle NULL value.

Convert.ToInt32 – It handles null value and converts value to default value ‘0’.

What is Finalize and Dispose ?

noreply@blogger.com (Venkat) — Thu, 21 Oct 2010 17:53:00 +0000

Finalize: - Automatically done by garbage collector to clean the resource memory.

Dispose: - Force the user to dispose objects.

Boxing and Unboxing ?

noreply@blogger.com (Venkat) — Thu, 21 Oct 2010 17:52:00 +0000

Boxing:

Implicit conversion of any value type to the type object.
Value types are stored on stack.
Reference or object type are stored on heap.

Unboxing:

Explicit conversion from object type to value type.

Reflection ?

noreply@blogger.com (Venkat) — Thu, 21 Oct 2010 17:52:00 +0000

You can see the metadata information through reflection mechanism.

Ability to inspect and manipulate programs elements at runtime.

It’s the process of runtime type discovery.

Reflection Services:

Load an assembly at runtime.
Enumerate members of a type.
Instantiate a new object.
Execute the members of an object.
Find out the information about a type .
Find out the information about a assembly
Inspect custome attributes applied to a type.
Create and compile new assembly.

What is Session ?

noreply@blogger.com (Venkat) — Thu, 21 Oct 2010 17:50:00 +0000

Session is used to store user details particularly userid and user information so once you set the information in session you can get the data anywhere in the project .

Syntax:

Session[“username”] = “Venkat”;

How to write stored procedure – give syntax ?

noreply@blogger.com (Venkat) — Thu, 21 Oct 2010 17:49:00 +0000

Create Procedue <procedureName>
(
Your parameter
)
As
Begin
< your Sql Statement>
End

To create a new Guid?

noreply@blogger.com (Venkat) — Thu, 21 Oct 2010 17:48:00 +0000

Guid getnewID = Guid.NewGuid();

Difference between timestamp and uniqueidentifier ?

noreply@blogger.com (Venkat) — Thu, 21 Oct 2010 17:46:00 +0000

TimeStamp:

Size – 8 bytes.
Note based on system date or time
To track the operation in tables on the database level.

Uniqueidentifier

16 – bytes.
Value is based on the computer MAC Addresss and system datetime.
It remains unique in any system in the world.

How to convert from string to GUID ?

noreply@blogger.com (Venkat) — Thu, 21 Oct 2010 17:46:00 +0000

String mystring = “xxxx-xxxx-xxxx-xxxx”;

Guid = new Guid(mystring);

Newid() = Globally unique identifier

NewSequentialId() – Globally sequential identifier

Where the session is stored ?

noreply@blogger.com (Venkat) — Thu, 21 Oct 2010 17:45:00 +0000

<sessionState mode =”InProc” cookieless=”False” timeout=”20”/>

By default Cookieless is set to false – so the session Id is stored in Cookies so as long as user navigating the page you can get the session from cookies.

If you set the cookieless =”True” the session id is stored on the browser url before the file name

Ex: http://yourserver/folder/(sessionid)/default.aspx

Drawback is if the user working on the site it has assigned some sessionId on the url , by giving the different url on Address bar and do some process once the user type same url at that time it will give different sessionid, the previous session will be lost and lost all of previous state.

Default timeout for session is 20 Mins.

Default timeout for Form authentication 30 Mins.

How to display the Name on Email to address

noreply@blogger.com (Venkat) — Thu, 21 Oct 2010 17:44:00 +0000

EX:

MailMessage msg = new MailMessage();

Msg.from = new mailAddress(“youraddress@gmail.com”, “Test”);

Form authentication Configuration

noreply@blogger.com (Venkat) — Thu, 21 Oct 2010 17:43:00 +0000

How to keep the session alive?

noreply@blogger.com (Venkat) — Thu, 21 Oct 2010 17:42:00 +0000

<sessionState timeout=”20” mode=”InProc” />

By default slidingexpiration is enabled = “true” so when the momen postback occurs or user utilizing the controls, session timeout counter is refreshed so the session remains active.

To get the Username from the masterPage while using login Control ?

noreply@blogger.com (Venkat) — Thu, 21 Oct 2010 17:41:00 +0000

String username = Page.User.Identity.Name;

How to get a random row from a table in SQL server ?

noreply@blogger.com (Venkat) — Thu, 21 Oct 2010 17:40:00 +0000

Select Top 1 columName from Tablename Order by newid()

How to get the last inserted ID from the table ?

noreply@blogger.com (Venkat) — Thu, 21 Oct 2010 17:34:00 +0000

There are two ways to get the ID of the last inserted record.
@Identity()
@Scope_Identity()

EX:
String Squlquery = “insert into tablename(categoryname) values (@categoryname);” + “Select Scope_Identity()”;

So use ExecuteScalar to get the ID of the last inserted Record.

Int getLastID = (int) cmd.ExecuteScalar();

Post Interview Question

noreply@blogger.com (Venkat) — Sat, 02 Oct 2010 19:17:00 +0000

Pos your Interview Question ..here..

In the comment box

you will get the answer for your question soon.

Thanks