多表联查，两表之间相互关联，不必定须要有主外键关系，字段匹配就行

Set @dlr = 15001; SELECT school.name AS schoolName, xq.xqmc AS xqmc, qy.mc as qymc, ly.bz as lymc, fj.bz as fjmc FROM t_xsgy_ssap ssap                 LEFT JOIN t_xsgy_cwgl cwgl ON cwgl.id=ssap.cwid  

>>阅读原文<<