I guess you'll have to write another trigger for the RowColumns table to validate ColumnId against the Columns table

>
>I'd tried that but when deleting a row in the Rows table I got a 'The DELETE statement conflicted with the REFERENCE restraint' error.
>?
>Thx,
>Viv
>
>>Keep the FK but set ON DELETE NONE
>>
>>>
>>>Thx. Thought that might be the answer ; got it working for cascading the deletes. But that leaves the other half of the equation : How to prevent insertions in the RowColumns table if the ColumnId doesn't exist in the Columns table ?
>>>
>>>Regards,
>>>Viv
>>>
>>>>You can replace one of ON DELETE CASCADE to RowColumns with a trigger.
>>>>