转自博客园
Johnny.3-技术随笔 笔按照自己的理解做个笔记，以下在Sql Server2005和Oracle92中都运行通过：
create table a(
aid varchar(2),
aname varchar(10),
bid varchar(2) );
create table b(
bid varchar(2),
bname varchar(10));
insert into a values('s1','sname1','c1');
insert into a values('s2','sname2','c2');
insert into a values('s3','sname3','c3');
insert into a values('s4','sname4','c4');
insert into a values('s5','sname5','c5');
insert into b values('c1','cname1');
insert into b values('c2','cname2');
insert into b values('c3','cname3');
insert into b values('c6','cname6');
insert into b values('c7','cname7');
--Iner Join和Join和, (如select * from a,b where a.id=b.id)，这三个效果一样.
select * from a , b where a.bid = b.bid;
select * from a join b on a.bid = b.bid;
select * from a inner join b on a.bid = b.bid;
--Left Join和Left Outer Join 左连接、左外连接，效果一样。
select * from a left join b on a.bid = b.bid;
select * from a left outer join b on a.bid = b.bid;
--Right Join和Right Outer Join 右连接、右外连接，效果一样。
select * from a right join b on a.bid = b.bid;
select * from a right outer join b on a.bid = b.bid;
--Full Join和Full Outer Join 全连接、全外连接，效果一样。
select * from a full join b on a.bid = b.bid;
select * from a full outer join b on a.bid = b.bid;
--Cross Join，不带where，即笛卡尔积。
select * from a Cross join b;
总结：只有以上的的连接词，像什么Left Inner Join、Right Full Join之类的组合都没有，想都别想！！
posted on 2009-02-20 11:04 Johnny.3 阅读(264) 评论(1) 编辑收藏 网摘