now im doing project in asp.net by using visual studio 2008.
im having some doubt in connectivity by usiny sql.So can anyone suggest some links to help me

What kind of issue are you having? Visual Studio allows you connect to a DB source without writing one item of code by using the wizards on the various controls.

Are you trying to connect to a local DB or remote DB?

http://www.asp.net has all sorts of tutorials for gettings started with asp.net, including how to connect to the database. Do you have a more specific question or problem?

You can connect to data base using ADO.Net framework .For example, the namespace System.Data.SqlClient has many usefull classes to connect to sql server database such as :SqlClient,SqlConnection,SqlAdapter and others see the below link
http://msdn.microsoft.com/en-us/library/system.data.sqlclient.aspx
Also the data connectivity using .net 3.5 and .net 4.0 includes the worlds of linq to entity and other technologies you can take a look on them.
You can use data source controls to connect asp.net controls to data base or to a query.Indeed, video tutorials would be usefull in this area