http://www.111cn.net/database/mysql/62555.htm
select * from a left join b on a.id=b.id left join c on b.id=c.id and ***
注意是用 join ... on ... and ...,还是用 join ... on ... where ...
(现在看来,这个用的真是太普遍了,且何止三个。)
http://www.111cn.net/database/mysql/62555.htm
select * from a left join b on a.id=b.id left join c on b.id=c.id and ***
注意是用 join ... on ... and ...,还是用 join ... on ... where ...
(现在看来,这个用的真是太普遍了,且何止三个。)