does a record exist? count vs limit vs both nested

Question

say you want to check if any rows match a query (just a true/false if the table contains any matches). which is preferred (and optionally, why)? or is there a better way?

SELECT COUNT(*) > 0 FROM someTable WHERE someField = someValue

or

SELECT someField = someValue FROM someTable WHERE someField = someValue LIMIT 1

or

SELECT COUNT(*) > 0 FROM (SELECT someValue FROM someTable WHERE someField = someValue LIMIT 1) someAlias;

http://stackoverflow.com/questions/4484974/the-quick-way-to-check-if-select-exists-returns-a-value-using-php — ethrbunny, Dec 15 '12 at 16:04

score 0 · Answer 1 · answered Dec 16 '12 at 19:40

0

I would use EXISTS:

SELECT EXISTS (SELECT * FROM someTable);

This returns 1 (True) if the subquery returns any rows at all, otherwise it returns 0 (False).

answered Dec 16 '12 at 19:40

Jeff H

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does a record exist? count vs limit vs both nested

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