"JBowler" wrote in news:uX3RFa9nEHA.1712
@tk2msftngp13.phx.gbl:

We considered that but in the UK a postcode is limited to very few
households. The chance exists but is rare.

Don't believe it. Fathers often give their names to their sons (and mothers
to daughters) so it is going to be more-than-averagely likely for the same
name to be present at the same address. The existence of nulls (what, you
mean you never, ever, don't know the postcode?) will complicate matters
further.

By all means have your form check for likely clashes (for example, use the
Form_BeforeUpdate event) but using the db engine to prevent them is going
to lead to very disgruntled users, not to say the data subjects.

Hope that helps


Tim F