关于MySql 查询语句的问题 LEFT JOIN

Question

我有一个结果集，然后我想要另一张表对着我的查询的结果有的显示内容，没有的显示空。
SELECT E.classname,E.classid,S.title,S.kjdata FROM phome_ecms_ssc S, phome_enewsclass E,(SELECT id FROM phome_ecms_ssc where classid = 26 and kjdate > UNIX_TIMESTAMP(NOW()) ORDER BY kjdate LIMIT 1) B where S.classid = 26 and S.classid = E.classid and S.id <= B.id ORDER BY S.id DESC LIMIT 10
这一段是我的的结果
phome_ecms_yuce
这张是我要关联的表

我真的没有用过 JOIN 最终我写的是

SELECT E.classname,E.classid,S.title,S.kjdata FROM phome_ecms_ssc S, phome_enewsclass E,(SELECT id FROM phome_ecms_ssc where classid = 26 and kjdate > UNIX_TIMESTAMP(NOW()) ORDER BY kjdate LIMIT 1) B where S.classid = 26 and S.classid = E.classid and S.id <= B.id ORDER BY S.id DESC LIMIT 10
LEFT JOIN phome_ecms_yuce Y ON S.classid = Y.wanfaid and S.title = Y.qihao and Y.jihuaid = 1

这个写法是错误的，求大神指点

Answer 1

left join是不能放在where后面的，如果是想要join前面生成的结果集的话，需要将生成结果集再join

select * from (SELECT E.classname,E.classid,S.title,S.kjdata FROM phome_ecms_ssc S, phome_enewsclass E,(SELECT id FROM phome_ecms_ssc where classid = 26 and kjdate > UNIX_TIMESTAMP(NOW()) ORDER BY kjdate LIMIT 1) B where S.classid = 26 and S.classid = E.classid and S.id <= B.id ORDER BY S.id DESC LIMIT 10 ) ls left join phome_ecms_yuce Y ON Y.wanfaid=ls.classid and Y.qihao=ls.title and Y.jihuaid = 1