- 在百度里面查来查去，mysql里面order by 和 GROUP BY放在一起用实在是超出了我的能力范畴，所以才去找了其他的办法（第三方太可恶了）
这里一共涉及三张表，以第一张表为主表进行左关联再左关联进行查询.
先查好每张表的数据，再进行左关联查询
select id,url,bz,scyxsj,zqjh,xcyxsj,sfzqsm,s.zt,z.high,z.medium,z.low,z.info from MBB left join (SELECT (id)rwid,mbb_id,zt FROM `SMRWB` as c WHERE cjsj = (SELECT max(cjsj) FROM SMRWB as d WHERE c.`mbb_id` = d.`mbb_id` GROUP BY `mbb_id`))s on MBB.id =s.mbb_id left join (SELECT smrwb_id, high,medium,low,info FROM `RWZXJLB` as a WHERE kssj = (SELECT max(kssj) FROM RWZXJLB as b WHERE b.`smrwb_id` = a.`smrwb_id` GROUP BY `smrwb_id`))z on s.rwid = z.smrwb_id where MBB.user_id = 1