From: | Jeff Frost <jeff(at)frostconsultingllc(dot)com> |
---|---|
To: | pgsql-sql(at)postgresql(dot)org |
Subject: | Check/unique constraint question |
Date: | 2006-03-05 08:25:58 |
Message-ID: | Pine.LNX.4.64.0603050015050.29717@discord.dyndns.org |
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Thread: | |
Lists: | pgsql-sql |
I have a table with the following structure:
Column | Type | Modifiers
------------+---------+-----------------------
active | boolean | not null default true
id | integer | not null
(other columns left out)
And would like to make a unique constraint which would only check the
uniqueness of id if active=true.
So, the following values would be acceptable:
('f',5)
('f',5)
('t',5)
But these would not be:
('t',5)
('t',5)
Basically, I want something like:
ALTER TABLE bar ADD CONSTRAINT foo UNIQUE(active (where active='t'),id)
But the above does not appear to exist. Is there a simple way to create a
check constraint for this type of situation, or do I need to create a function
to eval a check constraint?
--
Jeff Frost, Owner <jeff(at)frostconsultingllc(dot)com>
Frost Consulting, LLC http://www.frostconsultingllc.com/
Phone: 650-780-7908 FAX: 650-649-1954
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