1--echo # 2--echo # MDEV-13118 Wrong results with LOWER and UPPER and subquery 3--echo # 4 5SET @save_optimizer_switch=@@optimizer_switch; 6SET optimizer_switch=_latin1'derived_merge=on'; 7CREATE TABLE t1 AS SELECT REPEAT('a', 10) AS t LIMIT 0; 8SHOW CREATE TABLE t1; 9INSERT INTO t1 VALUES ('abcdefghi'),('ABCDEFGHI'); 10--sorted_result 11SELECT CONCAT(t2,'-',t2) c2 FROM (SELECT LOWER(t) t2 FROM t1) sub; 12--sorted_result 13SELECT CONCAT(t2,'-',t2) c2 FROM (SELECT UPPER(t) t2 FROM t1) sub; 14DROP TABLE t1; 15SET optimizer_switch=@save_optimizer_switch; 16