Re: Unique Constraint Based on Date Range

On Sat, 20 Sep 2003 18:55:34 -0400, Kevin Houle <kevin(at)houle(dot)org>
wrote:
> SELECT INTO result * FROM table_rates WHERE
> effective_date >= NEW.effective_date AND
> expiry_date <= NEW.expiry_date AND
> cost = NEW.cost;
> IF FOUND THEN
> RAISE EXCEPTION ''record overlaps with existing record'';
> END IF;

This only catches complete inclusion of an old range in the new one.
new b---------------------e
old b--------------e

Try
WHERE effective_date < NEW.expiry_date
AND expiry_date > NEW.effective_date

which also detects
new b--------------------e
old b-------------------e
old b------------------e
old b--------------------------------e

Servus
Manfred