UPDATE with SUBSELECT and ORDER BY
---------------------------------------------

Hi @ Postgres BUGS...

SITUATION:

I have a Table

id groupid orderby

1 1 10
2 1 20
3 1 30
4 1 40
5 2 10
6 2 20
10 2 30
11 2 40

and a UNIQUE INDEX on columns "groupid,orderby"

now i want to update

UPDATE
orderby SET orderby = orderby +10
WHERE groupid = 1;

-> FAILS because of UNIQUE INDEX

NOW I WANTED TO UPDATE REVERSE:

UPDATE
orderby SET orderby = orderby +10
WHERE groupid IN
( SELECT groupid
FROM TABLE WHERE group_id = 1
ORDER BY orderby DESC )
;

-> FAILS TOO... SEEMS LIKE THE ORDER BY "DESC" WONT BE USED ?!?


This is with Postgres Version 8.0.3


Regards,
Claus Pruefer


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claus.pruefer (AT) webcodex (DOT) de wrote:

This is a Known Issue(tm). (A "gotcha", some would say).

http://archives.postgresql.org/pgsql...0/msg00146.php
Surely you can find better references in the archives, but I'm too lazy.
(keywords: "deferrable unique constraint")

--
Alvaro Herrera http://www.CommandPrompt.com/
The PostgreSQL Company - Command Prompt, Inc.

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