Now I know the values in the field in question are unique - I have only 3 records.
But when I delete all the records from the table, I still get the above message. <SL> Are there other active connections? Have they committed all transactions? <SL> FB Indexes contain information for **all active transactions**, so if there are active transactions which can still see the old data . adding the new constraint would fail. Thanks Sean, I didn't think so but it's possible - I'll defer on this one. Alan
