CREATE TABLE t1(id INT);
INSERT INTO t1 VALUES (1),(2),(3),(4);
INSERT INTO t1 SELECT a.id FROM t1 a,t1 b,t1 c,t1 d;
SET SESSION debug="d,subselect_exec_fail";
SELECT SUM(EXISTS(SELECT RAND() FROM t1)) FROM t1;
SUM(EXISTS(SELECT RAND() FROM t1))
0
SELECT REVERSE(EXISTS(SELECT RAND() FROM t1));
REVERSE(EXISTS(SELECT RAND() FROM t1))
0
SET SESSION debug=DEFAULT;
DROP TABLE t1;