Date: Mon, 24 Feb 2003 19:53:00 +0200
From: "Victor Yegorov" <viy@pirmabanka.lv>
To: pgsql-sql@postgresql.org
Subject: Dynamic SELECT condition
Message-ID: <20030224175300.GC2841@pirmabanka.lv>
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Hello.

I'd like to know, is it possible to use returned data set values as
condition at runtime?

Here comes the details.
I have one table which links objects of various types into trees. Say, it h=
as
5 rows:

 parent_id | child_id
-----------+----------
 1         | 2
 1         | 3
 3         | 4
 3         | 5
 4         | 6
=20
Each parent_id and child_id are primary keys in some other tables (don't ma=
tter
which, with object details).

Say, I'd like to show user a tree for object_id =3D 3 on the web.

Is it possible to get the following result set with one SQL request:

 parent_id | child_id
-----------+----------
 3         | 4
 3         | 5
 4         | 6
=20
I mean, I know the id of a root object, it's 3. If I'll extract with
condition parent_id =3D 3, then I'll get only 2 rows. I'd like to have a
recursive result set - while there are records in the table for which
count(next_level_parent_id =3D=3D this_level_child_id) > 0, select parent_i=
d, child_id.

I hope you'll understand my problem.

Thanks in advance.

--
Victor Yegorov

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