sql update max smartries

Started by Vic Cekvenichover 21 years ago2 messagesgeneral
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#1Vic Cekvenich
cekvenich.vic@portalvu.com

I am trying to write a sigle command to update the max number from detail.

Something like:
update group set max_msgid=max(c.msgid)
from group g, content c
where g.id=c.g_id

So group is master, content is detail. I want group to stroe max(msgid)
from content.

Syntax help plz?
.V

#2Bruno Wolff III
bruno@wolff.to
In reply to: Vic Cekvenich (#1)
Re: sql update max smartries

On Thu, Oct 21, 2004 at 18:14:15 -0500,
Vic Cekvenich <cekvenich.vic@portalvu.com> wrote:

I am trying to write a sigle command to update the max number from detail.

Something like:
update group set max_msgid=max(c.msgid)
from group g, content c
where g.id=c.g_id

So group is master, content is detail. I want group to stroe max(msgid)
from content.

You don't want to put 'group' in the from clause, you will then be joining
'group' with itself (in addition to content).
Also you really don't want to join 'group' and 'content', but rather
'group' and (select c.g_id, max(c.msgid) from content group by g_id).
So the query should look something like (I didn't test this):
UPDATE "group" SET max_msgid=g.msgid
FROM (SELECT c.g_id, max(c.msgid) AS msgid FROM "content" c GROUP BY g_id) AS g
WHERE "group".id = g.g_id;