สอบถามการ Connect 2 Database C# กับ Sql Server 2005 ครับ

//connection sql
 SqlConnection con = new SqlConnection("data source=.\\sqlexpress;network library=dbmssocn;" +
           "initial catalog=DB1;user id=sa;password=adul");

        

        private void Form1_Load(object sender, EventArgs e)
        {
            DisplayRecords();
            DisplayRecords1();
        }
        private void DisplayRecords()
        {
            try
            {
                con.Open();
                DataTable dt = new DataTable();
                SqlDataAdapter da = new SqlDataAdapter("select gmas.standard,prdmas.wgt from phonebook.gmas inner join prd on gmas.gradecode = prdmas.gradecode ", con);
                da.Fill(dt);
                
                dataGridView1.DataSource = dt.DefaultView;
                con.Close();
            }
            catch (Exception error)
            {
                MessageBox.Show(error.ToString());
            }
            
        }

//เชื่อม database 1
SqlConnection con = new SqlConnection("data source=.\\sqlexpress;network library=dbmssocn;" +
           "initial catalog=DB1;user id=sa;password=adul");
//เชื่อม database 2
        SqlConnection con1 = new SqlConnection("data source=.\\sqlexpress;network library=dbmssocn;" +
           "initial catalog=phonebook;user id=sa;password=adul");

//แบบ join ข้อมูลคนละตาราง แต่ database เดียวกัน
con.Open();
                DataTable dt = new DataTable();
                SqlDataAdapter da = new SqlDataAdapter("select gmas.standard,prdmas.wgt from phonebook.gmas inner join prd on gmas.gradecode = prdmas.gradecode ", con);
                da.Fill(dt);