Re: Help with SQL

[Charles Wilt <charles.wilt@xxxxxxxxx>]

The query engine is optimized for joins.

Many times, EXISTS or a IN will be re-written as a join.

An exception join, as shown, will not bring try to bring in any data from
the child table.

Charles


On Fri, Dec 20, 2019 at 8:47 AM Darren Strong <darren@xxxxxxxxx> wrote:

> I've seen NOT EXISTS and JOINS suggested. My opinion is that a NOT EXSISTS
> will perform the best for you.  If you don't actually need a value from the
> child table, a join brings the possibility of a higher performance hit vs.
> the NOT EXISTS, which is accurately telling the optimizer that you don't
> want anything from the secondary table except to know if a record exists
> there.
>
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