SQl中的左連接配接，右連接配接，内連接配接，全連接配接，自連接配接的了解。
轉自部落格園
Johnny.3-技術随筆 筆
按照自己的了解做個筆記，以下在Sql Server2005和Oracle92中都運作通過：
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)，這三個效果一樣.
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 左連接配接、左外連接配接，效果一樣。
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 右連接配接、右外連接配接，效果一樣。
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 全連接配接、全外連接配接，效果一樣。
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，不帶where，即笛卡爾積。
select * from a Cross join b;
總結：隻有以上的的連接配接詞，像什麼Left Inner Join、Right Full Join之類的組合都沒有，想都别想！！
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posted on 2009-02-20 11:04 Johnny.3 閱讀(264) 評論(1) 編輯收藏 網摘