From: | "Magnus Naeslund(f)" <mag(at)fbab(dot)net> |
---|---|
To: | "Christopher Kings-Lynne" <chriskl(at)familyhealth(dot)com(dot)au>, <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: 7.4 Wishlist |
Date: | 2002-12-02 20:34:20 |
Message-ID: | 063201c29a42$316532f0$f80c0a0a@mnd |
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Christopher Kings-Lynne <chriskl(at)familyhealth(dot)com(dot)au> wrote:
>> Mysql is planning on making this work:
>>
>> SELECT id, @a:=COUNT(*), SUM(sum_col)/@a FROM table_name GROUP BY
>> id.
>>
>> Do we have anything like it (After a discussion with Tom i figure
>> no). User variables is nice, especially in these kind of queries.
>
> Well of course they have to make that work - they don't have
> subselects :P
>
> Chris
Yeah, but there is a point about running count(*) one time too many.
Say if i would like to get a prettyprinting query like this:
SELECT id, @a:=COUNT(*), sum_col::text||'/'@a::text FROM table_name;
That would be DAMN expensive doing with a subselect:
SELECT id, sum_col||'/'||(select COUNT(*) from tabe_name) FROM
table_name;
I know this example suck eggs, but you get the point where it hurts,
right?
Magnus - sorry for the dupe, chris
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