From: | "Scott Marlowe" <scott(dot)marlowe(at)gmail(dot)com> |
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To: | "Gavin Baumanis" <gavinb(at)eclinic(dot)com(dot)au> |
Cc: | pgsql-sql(at)postgresql(dot)org |
Subject: | Re: SELECT MAX returns wrong value |
Date: | 2007-12-14 17:24:14 |
Message-ID: | dcc563d10712140924h758ec6dep8129f9ef71968df9@mail.gmail.com |
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Lists: | pgsql-sql |
On Dec 13, 2007 5:09 PM, Gavin Baumanis <gavinb(at)eclinic(dot)com(dot)au> wrote:
> Hi Everyone,
>
> Sorry if I am missing something obvious but I think I have found a bug.
> If I perform the following SQL
>
> SELECT MAX(column) FROM table WHERE expression
>
> and there is no match, Postgres returns a record count of 1.
> There is no value in max, it is NULL.
that's because you got one record back. A null one, but a record none the less.
The standard way of doing this is:
select count(column) from table where expression.
since null columns don't get counted, it will return zero if they're all null.
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