sql server 2008 - DataAdapter.Update() doesn't work to update -
my sql statments follows insert statement works update , delete statements don't work purchase_invoiceno primary key column of purchase table value , insert value purchaseproduct table "select ident_current ('purchase') [purchase_invoiceno]" string deletecmd_purchaseproduct = @"delete purchaseproduct " + "purchaseproduct_no=@purchaseproduct_no , "+ "purchase_invoiceno=@purchase_invoiceno "; string updatcmd_purchaseproduct = "update purchaseproduct " + " set " + " purchaseproduct_serialno =@purchaseproduct_serialno" + ", purchase_invoiceno =@purchase_invoiceno" + ", productno =@productno" + " purchaseproduct_quantity =@purchaseproduct_quantity " + ", purchaseproduct_unit =@purchaseproduct_unit" + ", purchaseproduct_pric...