Best way to check for login details in asp.net

Why you don't want to use datareader. Can you clarify?

Sir,

Will it not be a security issue.. As it is continuously connected to database.. If it is not then how can i write a method to check for login details against database

No it is not a security issue. You can simply write a query and use ExecuteScalar to get the value

int userId = (int)cmd.ExecuteScalar()

select userid from users where username = @username and password = @password

Sir,

I am using 3 tier.. If you can show me a sample method i shall be grateful..

Thanks

You will not get 100% built sample anywhere on internet. I have given you query now you tell me where it is causing your trouble I'll help