How does asp.net connect to a database?

Asp tutorial. net how to connect to a database tutorial
The following is an example of connecting to the mssql database using asp.net tutorial c and querying the specified data.

String connstr = system. web. configuration. webconfigurationmanager. connectionstrings ["sqlconnstr"]. connectionstring; // Here
Sqlconnection conn = new sqlconnection (connstr );
Sqlcommand cmd = new sqlcommand ();
Cmd. connection = conn;
Cmd. commandtext = "select id, xingming, gh from users where gh> 600 ";
Try
        {
Conn. open ();
Sqldatareader dr = cmd.exe cutereader ();
This. gridview1.caption = "employee information table ";
This. gridview1.datasource = dr;
This. gridview1.databind ();

        }
Catch (sqlexception gh)
        {
Throw gh;

        }
Finally
        {
If (conn. state = connectionstate. open)
            {
Conn. close ();
                       
            }
       
        }

    }