Re: SQL problem: retrieve child records if existent

From: Stephane Faroult <sfaroult_at_oriole.com>
Date: Thu, 31 May 2001 12:18:20 -0700
Message-ID: <F001.00316934.20010531121523@fatcity.com>

Helmut Daiminger wrote:
>
> Hi!
>
> I have a SQL problem here, which I can't solve.
>
> I have a B-tree structure in a table (parentID, childID).
>
> If a parent has kids then select those kids. If not, select this parent.
>
> How do I code this in SQL? I tried using "connect by" but this doesn't
> include start point.
>
> Any idea?
>
> This is 8.1.6 on Win2k.
>
> Thanks,
> Helmut
>
> --
> Please see the official ORACLE-L FAQ: http://www.orafaq.com
> --
> Author: Helmut Daiminger
> INET: hdaiminger_at_vivonet.com

   select t.id, t.name
   from your_table t
   where t.id = what you are looking for

     and not exists (select null 
                     from your_table t2
                     where t2.parent_id = t.id)

   union
   select t.id, t.name
   from your_table t
   where t.parent_id = what you are looking for

 Index on parent_id, please.

Stephane Faroult
Oriole Corporation
Voice: +44 (0) 7050-696-269
Fax: +44 (0) 7050-696-449
Performance Tools & Free Scripts

---

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-- 
Please see the official ORACLE-L FAQ: http://www.orafaq.com
-- 
Author: Stephane Faroult
  INET: sfaroult_at_oriole.com

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Received on Thu May 31 2001 - 14:18:20 CDT