Gurjeet Singh wrote:
> On Sun, Sep 26, 2010 at 9:37 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>
> The SQL standard explicitly disavows any particular
> output row order unless there is a top-level ORDER BY. (In fact,
> unless things have changed recently an ORDER BY in a sub-select isn't
> even legal per spec.)
>
> Not sure about the SQL spec allowing it, but an ORDER BY followed by a
> LIMIT does have valid use cases in sub-selects.
Absolutely it does, but that is just a row *filtering* operation. You still
have to have a separate ORDER BY in the outermost query to get result rows
output in a particular order. -- Darren Duncan