Re: Unique Constraint Based on Date Range

On Sat, 20 Sep 2003 18:55:34 -0400, Kevin Houle <kevin@houle.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
 

TryWHERE 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
 

ServusManfred