ขอความรู้เพิ่มเติมเกี่ยวกับ MS Sql Server Connection ครับ

                using (DB_Entities db = new DB_Entities())
                {
                    var ds = (from c in db.VIEW_APPROVER
                              where c.CODE == sDestination
                              select new { c.TYPE }).FirstOrDefault();
                    if (ds != null)
                    {
                        return ds.TYPE;
                    }
                    else
                    {
                        return string.Empty;
                    }

                }

           using(clsDBHelper dbHelper = new clsDBHelper())
	   {

		    string CommandString = @"select * from myTable";
		    DataTable dt = dbHelper.OpenDataTable(CommandString, "myTable");

		    ddl.DataSource = dt;
		    ddl.DataTextField = "Description";
		    ddl.DataValueField = "ID";
		    ddl.DataBind();

		    if (sFirstItem != string.Empty)
		    {
			ddl.Items.Insert(0, new ListItem(sFirstItem, string.Empty));
		    }

		    if (sSelected != string.Empty)
		    {
			ddl.SelectedIndex = ddl.Items.IndexOf(ddl.Items.FindByValue(sSelected));
		    }

	    }