create table l as
select ‘left_1‘ as str,‘1‘ as v from dual union all
select ‘left_2‘ ,‘2‘ as v from dual union all
select ‘left_3‘ ,‘3‘ as v from dual union all
select ‘left_4‘ ,‘4‘ as v from dual ;
create table r as
select ‘right_3‘ as str,‘3‘ as v, 1 as status from dual union all
select ‘right_4‘ as str,‘4‘ as v, 0 as status from dual union all
select ‘right_5‘ as str,‘5‘ as v, 0 as status from dual union all
select ‘right_6‘ as str,‘6‘ as v, 0 as status from dual ;
select * from l; --where l.v not in (select r.v from r )
select * from r
--1. inner join 返回两表相匹配的数据 即 交集
select l.str as left_str,r.str as right_str from l
inner join r on l.v=r.v
order by 1,2;
select l.str as left_str,r.str rigth_str from l,r
where l.v=r.v
order by 1,2;
--2.left join 左表为主表，左表返回全部数据，右表只返回与左表相匹配的数据
select l.str as left_str,r.str right_str from l
left join r on l.v=r.v
order by 1,2;
select l.str as left_str,r.str as right_str from l,r
where l.v=r.v(+)
order by 1,2;
select l.str as left_str,r.str as right_str from l,r
where l.v=r.v
order by 1,2;
--3.right join 右表为主表，左表只返回与右表相匹配的数据
select l.str as left_str,r.str as right_str from l
right join r on l.v=r.v
order by 1,2;
select l.str as left_str,r.str right_str from l,r
where l.v(+)=r.v
order by 1,2;
--4. 左右表均返回全部的数据，但是只有相匹配的数据显示在一行，非匹配的数据只显示一个表的数据
select l.str as left_str,r.str as right_str from l
full join r on r.v=l.v
order by 1,2;
谈谈oracle里的join、left join、right join
原文：http://www.cnblogs.com/iyoume2008/p/6395648.html