Thanks for the reply, David. I do actually validate the XML stored in the database: the XML column has an associated schema. However, I have since modified the...

Thanks for the reply, GSquared. The database schema is as follows. tblMap has a FK to tblSurvey (SurveyID), as you said; however, its primary key is actually two...

It seems that the devil was in the detail ... having read the above comments more closely, I have now managed to set my constraint with this syntax (for the...

Thanks for the quick replies! The constraint check refers to two other tables: is there a way of constructing a foreign key that refers to two tables rather than...

I can't remember, I'm afraid -- so clearly nothing useful!

That's excellent! Now working perfectly -- thank you very much indeed.

Thanks very much for your reply; those articles you suggested were very informative. In the end, I couldn't find a way of doing it in T-SQL but managed to...

Nice one, SQL Server Guy: that worked for me, too.

Fantastic, Bob -- that's exactly what I needed. Thanks a million!