From: Scott Marlowe <scott.marlowe@gmail.com>
To: emilu@encs.concordia.ca
Cc: pgsql-sql@postgresql.org
Subject: Re: case when... end in update clause?
Date: Wed, 12 Mar 2008 09:19:15 -0700
Message-ID: <dcc563d10803120919w5d26ff5amb7c0cf10cfcb99df@mail.gmail.com> (raw)
In-Reply-To: <47D8009D.6000703@encs.concordia.ca>
References: <47D7FB06.10707@encs.concordia.ca>
<dcc563d10803120901j5f6bd4as8eae1320318b7060@mail.gmail.com>
<47D8009D.6000703@encs.concordia.ca>
On Wed, Mar 12, 2008 at 9:11 AM, Emi Lu <emilu@encs.concordia.ca> wrote:
> >>
> >> I use one small Example, table: test
> >> =============================
> >> id
> >> ==
> >> 5
> >> 6
> >> 8
> >>
> >> try to update test.id
> >>
> >>
> >> update test
> >>
> >> case
> >> when id =5 then SET id = 6
> >> end
> >> ;
> >
> > would this work:
> >
> > update test set id=5 where id=6;
> >
>
> No. I provide one small fake example.
>
>
> I want to know how to use case when in update/set clause as the following:
>
> update test
> set id = case when id = 5 then 6 else id end;
Well, I think my point stands, that this stuff really belongs in a
where clause. The way you're doing it it updates ALL the rows whether
it needs to or not, my way only updates the rows that need it. How
about a REAL example of what you're trying to do. There may well be a
more efficient way of doing this than using a case statement. Or
not...
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To: pgsql-sql@postgresql.org
Cc: scott.marlowe@gmail.com, emilu@encs.concordia.ca
Subject: Re: case when... end in update clause?
In-Reply-To: <dcc563d10803120919w5d26ff5amb7c0cf10cfcb99df@mail.gmail.com>
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