[is_absent]

Drualex
а где там left join? и зачем нужен лимит во втором случае?

create table t1 (
  id int unsigned not null auto_increment,
  primary key (id)
);

insert into t1 values(1);
insert into t1 values(2);
insert into t1 values(3);
insert into t1 values(4);
insert into t1 values(5);
insert into t1 values(6);
insert into t1 values(7);
insert into t1 values(8);
insert into t1 values(9);
insert into t1 values(10);
insert into t1 values(12);
insert into t1 values(13);
insert into t1 values(14);
insert into t1 values(123);

create table t2 (
  id int unsigned not null auto_increment,
  primary key (id)
);
insert into t2 values(1);
insert into t2 values(2);
insert into t2 values(4);
insert into t2 values(6);
insert into t2 values(8);
insert into t2 values(100);

select * from t1 left join t2 on t2.id = t1.id limit 0, 4

вот. у меня стоит mysql 3.23, 4.0, 5.. на всех запрос прошел.