isDBNUll 问题?
解决方法:
txtInvNo.Text = oGrnRow.Inv_No is System.DBNull?"":(string)oGrnRow.Inv_No.Trim();
if(!oDataRow.Isven_noNull())
txVenNo.Text = oDataRow.ven_no;
txtInvNo.Text = oGrnRow.Inv_No is System.DBNull?"":(string)oGrnRow.Inv_No.Trim();
if(!oDataRow.Isven_noNull())
txVenNo.Text = oDataRow.ven_no;