Duplicate key

[Peter van Mierlo]

hi,

I use Delphi 6 / MySQL 5.x / DevArt MyDAC components. The tables is a type InnoDB and i would like to prevent duplicate values on a table. There's a unique index on a fieldname item_name. To prevent dupicates values i used a OnPostError with the following code below. In the datamodule i created a const. like this:

const
{Declare constants we're interested in}
ER_DUP_KEY = 1062;

The code below is the OnPostError

if (E is EMyError) then begin
if (EMyError(E).ErrorCode=ER_DUP_KEY) then begin
Application.MessageBox('De door u ingevoerde waarde bestaat reeds'+#10+'en mag niet dubbel worden geregistreerd!.', 'Mededeling', MB_OK+MB_ICONEXCLAMATION+MB_DEFBUTTON1+MB_APPLMODAL);
dmTables.qry_item.cancel;
Action := daAbort;
end;
end;

For some reasons when entering a duplicate item_name in this example the application terminates and i can't figure out why or where. Is this procedure correct, is the const. value correct or are there other methods to prevent dupplicates.

Regards Peter