From: Manfred Koizar <mkoi-pg@aon.at>
To: Rajesh Kumar Mallah <mallah@trade-india.com>
Cc: Christoph Haller <ch@rodos.fzk.de>
Cc: pgsql-sql@postgresql.org
Subject: Re: getting rid of "Adding missing FROM-clause entry...."
Date: Thu, 17 Apr 2003 18:02:12 +0200
Message-ID: <6ijt9vgiapkddv4o7cvj9rjprbmdkkcd8b@4ax.com> (raw)
In-Reply-To: <200304172122.17761.mallah@trade-india.com>
References: <3E9EB59F.B01FBF60@rodos.fzk.de>
<200304172021.28073.mallah@trade-india.com>
<dbht9vctbp8p6cmt5jt8rvaqb8tf34p2ci@4ax.com>
<200304172122.17761.mallah@trade-india.com>
On Thu, 17 Apr 2003 21:22:17 +0530, Rajesh Kumar Mallah
<mallah@trade-india.com> wrote:
>BTW any idea why the query which i posted is not
>working? and issuing a NOTICE.
I guess, in
UPDATE t1
SET ...
FROM (SELECT ... FROM t2
WHERE t2.id = t1.id);
the subselect is not correlated because t1 and the subquery are on the
same level. So the subquery is treated like a standalone query and as
it does not have t1 in its FROM clause, t1 is added automatically.
Then the result of the subquery is joined to each row of t1 for the
update. This also explains why all rows were updated to the same
values.
Servus
Manfred
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To: pgsql-sql@postgresql.org
Cc: mkoi-pg@aon.at, mallah@trade-india.com, ch@rodos.fzk.de
Subject: Re: getting rid of "Adding missing FROM-clause entry...."
In-Reply-To: <6ijt9vgiapkddv4o7cvj9rjprbmdkkcd8b@4ax.com>
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