id select_type table type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t3 ALL NULL NULL NULL NULL 2 100.00
1 SIMPLE t2 ALL NULL NULL NULL NULL 0 0.00 Using where
1 SIMPLE t1 ALL NULL NULL NULL NULL 3 100.00 Using where
Warnings:
Note 1003 select `test`.`t3`.`b` AS `b`,`test`.`t1`.`a` AS `a` from `test`.`t3` left join (`test`.`t2` join `test`.`t1`) on((`test`.`t3`.`a` <> 0)) where ((`test`.`t1`.`a` = `test`.`t1`.`a`) or (`test`.`t3`.`b` <> 0))