Login Code in ASP.Net using C#

using DataReader :

Sqlconnection con = new sqlconnection("your conectionstring");

Sqlcommand cmd = new sqlcommand();

cmd.commandtext = "select * from table";

cmd.connection = con;

if (con.state==connectionstate.closed) con.open();

SqlDatareader dr = cmd.executereader();

while(dr.read)

{

       if ( dr["Username"] == textbox1.text.trim() && dr["Password"] == textbox2.text )

       {

                 response.redirect("Homepage.aspx");

               return;

        }

}