Shortcut evaluation in OR or IN

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От Tim Uckun
Тема Shortcut evaluation in OR or IN
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Msg-id CAGuHJrN7VBbCeNV0XfP8oJUH-Stdd_aBCcZ_ObECv1E0ijARdQ@mail.gmail.com
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Ответы Re: Shortcut evaluation in OR or IN  (Richard Poole <rp@guests.deus.net>)
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Say I have a select like this.

SELECT * FROM table where field = X OR field = Y limit 1

And I have two records one that matches X and one that matches Y will I always get X because the evaluation will stop after the first clause in the OR matches?

What about for IN (X, Y)

how about if I am doing an update

UPDATE table1 set x=table2.y where table1.field1 = table2.field1 OR table1.field2=table2.field2

Will it update based on field1 if both fields match?


Basically I want to know if and how OR shortcuts the evaluation.

Thanks.

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