Re: Help with SQL -- MIDRANGE-L

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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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