//open conn
            SqlConnection myConnection = new SqlConnection("Data Source=(LocalDB)\\MSSQLLocalDB;AttachDbFilename=|DataDirectory|\\dbUser.mdf;Integrated Security=True");
            myConnection.Open();

            //command Sql ดึงเฉพาะที่ใช้
            //SELECT * FROM tbUser WHERE Username= 'PhetAdmin' and Password='456789'
            SqlCommand myCommand = new SqlCommand("SELECT * FROM tbUser WHERE Username= 'PhetAdmin' and Password='456789", myConnection);
            SqlDataReader myDatareader = myCommand.ExecuteReader();
            //3
            myDatareader.Read();
            //close conn
            myConnection.Close();