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* Update from same table
@ 2004-02-04 16:46 Jürgen Cappel <email@juergen-cappel.de>
0 siblings, 1 reply; 2+ messages in thread
From: Jürgen Cappel @ 2004-02-04 16:46 UTC (permalink / raw)
To: pgsql-sql
Hello,
I want to update columns in a table that match a fixed key
from the same column of the same table matching another fixed key.
There can be several tuples per key distinguished by a secondary id.
Tuples are unique with the combined keys. Maybe a query could look
something like this:
UPDATE a.mytable from b.mytable
SET a.mycolumn = b.mycolumn
WHERE a.firstid = some_key
AND b.firstid = some_other_key
AND a.secondaryid = b.secondaryid;
But it's a syntax error. I tried a subselect but i'm failing to connect
the subselect's 2nd ID with the update's 2nd ID. Any help ? Thanks,
Jürgen
^ permalink raw reply [nested|flat] 2+ messages in thread
* Re: Update from same table
@ 2004-02-04 17:28 Josh Berkus <josh@agliodbs.com>
parent: Jürgen Cappel <email@juergen-cappel.de>
0 siblings, 0 replies; 2+ messages in thread
From: Josh Berkus @ 2004-02-04 17:28 UTC (permalink / raw)
To: Jürgen Cappel <email@juergen-cappel.de>; pgsql-sql
Jurgen,
> UPDATE a.mytable from b.mytable
> SET a.mycolumn = b.mycolumn
> WHERE a.firstid = some_key
> AND b.firstid = some_other_key
> AND a.secondaryid = b.secondaryid;
Very close, actually; you just need to fix the table alias:
UPDATE mytable
FROM mytable as b
SET mytable.mycolumn = b.mycolumn
WHERE mytable.firstid = some_key
AND b.firstid = some_other_key
AND mytable.secondaryid = b.secondaryid;
AFAIK, one can't alias a table name in an UPDATE clause. So for that instance
of the table, you need to use the full name.
--
-Josh Berkus
Aglio Database Solutions
San Francisco
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2004-02-04 16:46 Update from same table Jürgen Cappel <email@juergen-cappel.de>
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