CODEWITHSUNDEEP
mysqlsubquery
Konstantin Vahrushev
Konstantin Vahrushev

Reputation: 1208

How many times const subquery in select is executed?

I have query:

SELECT id, (SELECT `name` from `config` WHERE id = 1) AS 'config' FROM customers

How many times is the subquery executed? Does MySql cache this subquery constant or does it execute it for every row?

Upvotes: 2

Views: 958

Answers (1)

ArSeN
ArSeN

Reputation: 5258

For a simple question here is your simple answer:

The subquery is only executed once, and the result is indeed held in a cache. It does NOT get executed for each row. That is, of course, unless you add a modifier such as SQL_NO_CACHE to it.

Upvotes: 2

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