mysql的关联查询求和

SELECT yfdj,sum(shu),sum(cb),sum(glcb),sum(fk) FROM client a

LEFT JOIN song b ON a.id = b.cid

LEFT JOIN lai c ON a.id = c.cid

GROUP BY yfdj

select t1.*,IFNULL(t2.num, 0) jf/** 积分*/

from (select * from A)t1, (select userid, sum(jifen) num from B group by userid)t2

where t1 left join t2 on t1.userid = t2.userid

/** sql未测试,理论可行 */

这个关联查询一下就可以

select a.ida as id ,(a.numa+isnull(b.numb,0)) as num from sa a left join sb b on a.ida=b.idb

union all

select b.idb as id ,b.numb as num from sa a right join sb b on a.ida=b.idb where a.ida is null

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