第一张表:SELECT a.qybh,a.qymc,a.xmyjid,a.xmmc,a.yjxmbh,a.zbtzsrq,a.zbj,a.jsdw,a.htj,a.xmdz,a.jgysrq FROM gzcc_xmyj a第二张表:select xmyjid,gclb,fbtz,sl from gzcc_xmgm通过xmyjid关联后,通过查询参数,数据要几十秒才能出来:SELECT a.qybh,a.qymc,a.xmyjid,a.xmmc,a.yjxmbh,a.zbtzsrq,a.zbj,a.jsdw,a.htj,a.xmdz,a.jgysrq,b.gclb,b.fbtz,b.sl FROM gzcc_xmyj aleft join (select xmyjid,gclb,fbtz,sl from gzcc_xmgm) bon a.xmyjid = b.xmyjid或者三张表联合查询 时的 sql优化 没有写参数sql 是直接写在查询表上