Posted by Gert-Jan Strik on 02/19/07 22:32

bbla32@op.pl wrote:
>
> On Feb 19, 10:31 pm, "Tibor Karaszi"
> <tibor_please.no.email_kara...@hotmail.nomail.com> wrote:
> > You are missing naming the derived table. Note the AS tbl at the end of the inner query:
> >
> > SELECT ...
> > FROM
> > (
> > SELECT ... FROM...
> > ) AS tbl
> > WHERE ...
> > GROUP BY...
>
> Thanks!
>
> Can I write a faster query?

A few tips:
- Only select the columns that you need in the derived table. IOW,
change "DM.*" to "DM.ID"

- Make sure you have proper indexes in place. For example on
DocumentMessages(SenderID,ObsoleteDate) and on
DocumentMessages(ReceiverPersonID,ObsoleteDate)

- Remove unnecessary IN clauses

Gert-Jan

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