insert into a1 values(1,'123');
insert into a1 values(2,'aaa');
insert into a1 values(3,'nnn');
insert into a1 values(4,'aaa');
insert into a2 values(1,'123');
insert into a2 values(2,'aaa');
select * from a1,a2 where a1.id=a2.id(+);
select * from a1 left join a2 on a1.id=a2.id;
select * from a1,a2 where a1.id=a2.id(+) and a2.name='aaa'
select * from a1,a2 where a1.id=a2.id(+) and a2.name(+)='aaa'