Oracle数据查询时经常用到的关联

create table ab
(
ab_id  number(5),
ab_name varchar2(30)
);

create table bb
(
bb_id  number(5),
bb_name varchar2(30)
);

insert into ab(ab_id,ab_name) values(1,'1ab_name');
insert into ab(ab_id,ab_name) values(2,'2ab_name');
insert into ab(ab_id,ab_name) values(3,'3ab_name');

insert into bb(bb_id,bb_name) values(1,'1bb_name');
insert into bb(bb_id,bb_name) values(2,'2bb_name');
insert into bb(bb_id,bb_name) values(4,'4bb_name');
insert into bb(bb_id,bb_name) values(6,'6bb_name');

select a.ab_id,a.ab_name,b.bb_name from ab a,
              bb b
where a.ab_id=b.bb_id;

AB_ID AB_NAME BB_NAME
1 1ab_name 1bb_name
2 2ab_name 2bb_name

select ab_id,ab_name, bb_name 
from ab a left join  bb b
on a.ab_id=b.bb_id;
同
select ab_id,ab_name, bb_name 
from ab a , bb b
where a.ab_id=b.bb_id(+);

AB_ID AB_NAME BB_NAME
1 1ab_name 1bb_name
2 2ab_name 2bb_name
3 3ab_name

select ab_id,ab_name, bb_name 
from ab a right join  bb b
on a.ab_id=b.bb_id;
同
select ab_id,ab_name, bb_name 
from ab a , bb b
where a.ab_id(+)=b.bb_id;

AB_ID AB_NAME BB_NAME
1 1ab_name 1bb_name
2 2ab_name 2bb_name
4bb_name
6bb_name

select ab_id,ab_name, bb_name 
from ab a full join  bb b
on a.ab_id=b.bb_id;

AB_ID AB_NAME BB_NAME
1 1ab_name 1bb_name
2 2ab_name 2bb_name
3 3ab_name 
6bb_name
4bb_name