From: Scott Marlowe <scott.marlowe@gmail.com>
To: Gavin Baumanis <gavinb@eclinic.com.au>
Cc: pgsql-sql@postgresql.org
Subject: Re: SELECT MAX returns wrong value
Date: Fri, 14 Dec 2007 11:24:14 -0600
Message-ID: <dcc563d10712140924h758ec6dep8129f9ef71968df9@mail.gmail.com> (raw)
In-Reply-To: <4761BBA7.7030800@eclinic.com.au>
References: <4761BBA7.7030800@eclinic.com.au>
On Dec 13, 2007 5:09 PM, Gavin Baumanis <gavinb@eclinic.com.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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To: pgsql-sql@postgresql.org
Cc: scott.marlowe@gmail.com, gavinb@eclinic.com.au
Subject: Re: SELECT MAX returns wrong value
In-Reply-To: <dcc563d10712140924h758ec6dep8129f9ef71968df9@mail.gmail.com>
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