Does MySQL Short Circuit the IF() function?

Question

I need to query data from a second table, but only if a rare set of conditions in the primary table is met:

SELECT ..., IF(a AND b AND c AND (SELECT 1 FROM t         


        

Answer 1

With J. Jorgenson's help I came up with my own test case. His example does not try to short circuit in the condition evaluation, but using his idea I came up with my own test and verified that MySQL does indeed short-circuit the IF() condition check.

SET @var:=5;
SELECT IF(1 = 0 AND (@var:=10), 123, @var); #Expected output: 5
SELECT IF(1 = 1 AND (@var:=10), @var, 123); #Expected output: 10

On the second example, MySQL is properly short-circuiting: @var never gets set to 10.

Thanks for the help J. Jorgenson!