505
505
explain (select * from t1 where a=1) union (select * from t1 where b=1);
506
506
id select_type table type possible_keys key key_len ref rows Extra
507
507
1 PRIMARY t1 const PRIMARY PRIMARY 4 const 1
509
509
NULL UNION RESULT <union1,2> ALL NULL NULL NULL NULL NULL
511
511
create table t1 ( id int not null auto_increment, primary key (id) ,user_name text );