Re: Using SUBSELECT in CHECK expressions

On Wednesday, November 5, 2003, at 06:26 AM, Tom Lane wrote:
> If you are satisfied with only a one-directional constraint (apply the
> check just when the constrained table is modified), you can have it
> today.
> Just put the SELECT into a function that's called by the CHECK
> expression.

Tom, you've just provided the solution to something I've been thinking
about a lot. I really have to start thinking in terms of functions. Are
there any restrictions on the function used in the CHECK, i.e., it must
be STRICT or IMMUTABLE? I took a quick look at the developer docs
(thinking they'd be for 7.4RC1. I was happily suprised to see they're
already labeled 7.5 dev!)

Michael
grzm myrealbox com