Question

I’m trying to write bits of code to a Microsoft access database from Delphi. I’m getting data from a TStringGrid. The first column has the ItemID, and the 2nd column has the Quantity. I’d like it to loop through the TStringGrid and save each row as a reperate row in my database and also save the Order ID with it on every column (The order ID stays the same for each order so that doesn’t need to change) .

I’m getting an error when running which says

“Project Heatmat.exe raised an exception class EVarientInvalidArgError with message ‘Invalid Argument’. Process Stopped.”

I can’t figure out why it’s giving me this error, and as you can probably see i’m not very good at coding yet. Any help would be appreciated!

Thank you.

procedure TCreateNewOrder.btnSaveClick(Sender: TObject);
var 
  intNumber, count : integer;
begin
  Count:= 0;
  if messagedlg ('Are you sure?', mtWarning, [mbyes, mbno], 0) = mryes then
  begin
    with HeatmatConnection.HeatmatDatabase do
    begin
      intNumber:= TBLOrder.RecordCount;
      TBLOrder.Append;

      TBLOrder['CustomerID']:= CompanyName.ItemIndex+1;
      TBLOrder['OrderID']:= intNumber +1;

      for count:= 1 to StringGrid1.RowCount-1 do
      begin
        TBLOrderedItem.Append;
        TBLOrderedItem['OrderID']:= intNumber+1;
        TBLOrderedItem['ItemID']:= StringGrid1.Cells[1, count];
        TBLOrderedItem['Quantity']:= StringGrid1.Cells[2, count];
        TBLOrderedItem.Post;
      end;
    end;
  end;
end;

Answer 1

TStringGrid cells are strings. trying to assign a string directly to a numeric field will raise an Exception.

So a good practice is to assign values to database fields via AsString, AsInteger, AsBoolean etc… this will make the correct conversion.

In your code use:

TBLOrderedItem.FieldByName('ItemID').AsString := StringGrid1.Cells[1, count];    

The same is true for Quantity.

To assign an Integer value use:

TBLOrderedItem.FieldByName('OrderID').AsInteger := intNumber + 1;

---

BTW, you are forgetting TBLOrder.Post i.e:

....
TBLOrder.Append;
TBLOrder.FieldByName('CustomerID').AsInteger := CompanyName.ItemIndex + 1;
TBLOrder.FieldByName('OrderID').AsInteger := intNumber + 1;
TBLOrder.Post;
...

Finally, I would also suggest to rename TBLOrder to tblOrder so that it’s name wont imply that it is a Type.