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From: Josh Berkus <josh@agliodbs.com>
Organization: Aglio Database Solutions
To: Adam Sherman <adam@tritus.ca>, pgsql-sql@postgresql.org
Subject: Re: Locating all Children given Set of Parents
Date: Tue, 13 May 2003 09:47:46 -0700
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Adam,

> I have three tables: parents, children & parent_child_mm.
>
> (So Parents and Children are in a Many-to-Many relationship.)
>
> Given a set of Parents, say 1, 2 & 3, how do I retrieve all children in an
> efficient manner? (I want each child to appear only once.)

Easy:

Select children.*
from children where exists (select pc_id=20
	from parent_child
	where pc.child_id =3D children.id
	and pc.parent_id IN ($parent_id_list)
	);

--=20
Josh Berkus
Aglio Database Solutions
San Francisco