--disable_warnings DROP TABLE IF EXISTS t1; --enable_warnings # A column dt1 DATETIME or dt1 INTEGER NOT NULL would be harmless. # MyISAM and InnoDB show the same wrong warning. CREATE TABLE t1 ( dt1 DATETIME NOT NULL); # This is needed. SET SESSION SQL_MODE = 'NO_ZERO_DATE'; # With "WHERE t1.dt1 IS NULL" comes a wrong warning # Warnings: # Warning 1292 Incorrect datetime value: '0' for column 'dt1' at row 1 # "WHERE t1.dt1=t2.dt1" is harmless SELECT COUNT(*) FROM t1 WHERE t1.dt1 IS NULL; SELECT COUNT(*) FROM t1 WHERE t1.dt1 = '2001-01-01 17:33:00'; DROP TABLE t1;