Valerii Kravchuk added a comment - 2016-06-15 08:03 I can reproduce this with 10.1.13 also: C:\Program Files (x86)\MariaDB 10.1\bin>mysql -uroot -proot -P3316 test Welcome to the MariaDB monitor. Commands end with ; or \g. Your MariaDB connection id is 2 Server version: 10.1.13-MariaDB mariadb.org binary distribution   Copyright (c) 2000, 2016, Oracle, MariaDB Corporation Ab and others.   Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.   MariaDB [test]> drop table t1; Query OK, 0 rows affected (0.47 sec)   MariaDB [test]> create table t1(c1 int); Query OK, 0 rows affected (0.19 sec)   MariaDB [test]> insert into t1 values(1); Query OK, 1 row affected (0.14 sec)   MariaDB [test]> select * from t1 where ( (c1 is not null) >= (not true) ) is not null; Empty set (0.08 sec)   MariaDB [test]> select c1, c1 is not null, not true, ((c1 is not null) >= (not true)) as a from t1; +------+----------------+----------+---+ | c1 | c1 is not null | not true | a | +------+----------------+----------+---+ | 1 | 1 | 0 | 1 | +------+----------------+----------+---+ 1 row in set (0.00 sec)   MariaDB [test]> select c1, c1 is not null, not true, ((c1 is not null) >= (not true)) is not null as a from t1; +------+----------------+----------+---+ | c1 | c1 is not null | not true | a | +------+----------------+----------+---+ | 1 | 1 | 0 | 1 | +------+----------------+----------+---+ 1 row in set (0.00 sec)   MariaDB [test]> select c1, c1 is not null, (((c1 is not null) >= (not true)) is not null) as a from t1 where ( (c1 is not null) >= (not true) ) is not null; Empty set (0.00 sec)   MariaDB [test]> explain extended select c1, c1 is not null, (((c1 is not null) > = (not true)) is not null) as a from t1 where ( (c1 is not null) >= (not true) ) is not null; +------+-------------+-------+------+---------------+------+---------+------+--- ---+----------+-------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | ro ws | filtered | Extra | +------+-------------+-------+------+---------------+------+---------+------+--- ---+----------+-------------+ | 1 | SIMPLE | t1 | ALL | NULL | NULL | NULL | NULL | 1 | 100.00 | Using where | +------+-------------+-------+------+---------------+------+---------+------+--- ---+----------+-------------+ 1 row in set, 1 warning (0.06 sec)   MariaDB [test]> show warnings\G *************************** 1. row *************************** Level: Note Code: 1003 Message: select `test`.`t1`.`c1` AS `c1`,(`test`.`t1`.`c1` is not null) AS `c1 i s not null`,(((`test`.`t1`.`c1` is not null) >= (not(1))) is not null) AS `a` fr om `test`.`t1` where (((`test`.`t1`.`c1` is not null) >= <cache>((not(1)))) is n ot null) 1 row in set (0.00 sec)   MariaDB [test]> select 1 is not null; +---------------+ | 1 is not null | +---------------+ | 1 | +---------------+ 1 row in set (0.00 sec) So, it seems expression is evaluated differently somehow when it's in WHERE clause comparing to it's value in SELECT clause.

Elena Stepanova added a comment - 2016-06-15 12:12 Importantly, in order to reproduce the problem, the table needs to be InnoDB (not MyISAM). drop table if exists t1; create table t1(c1 int ) engine=InnoDB; insert into t1 values (1); select * from t1 where ( (c1 is not null ) >= ( not true ) ) is not null ; bar , please take a look, maybe it falls into your area. Please feel free to modify 'Fix version/s' field as you like.

Alexander Barkov added a comment - 2016-06-22 12:25 The problem is also repeatable with MyISAM, with more than one records inserted: drop table if exists t1; CREATE TABLE t1 (c1 INT ) ENGINE=MyISAM; INSERT INTO t1 VALUES (1),(2),(3); SELECT * FROM t1 WHERE ((c1 IS NOT NULL ) >= ( NOT TRUE )) IS NOT NULL ; returns empty set.