SQL in constraints II

We have a table with a date range on it i.e. start and end dates. We want to make sure that for any particular person (EMPNO???) that the date ranges entered do not overlap those of any existing records.

How best to implement this?

We thought

1. constraint, but you can't put SQL in it.
2. database trigger. This would give us a mutating table though, we suspect as we need to query the table being inserted (or updated) into.
3. application (Forms) code. This will work but we'd like the extra safety net of testing at the server level also.

Any ideas anyone?

Alan Received on Thu Mar 04 1999 - 10:40:16 CST