多表都要跟据一共有的列分组统计

b表：要select cid,sum(count) from b where cid=1 group by cid;

 

a表: 要select cid,sum(amount) from a where cid=1 group by cid;

 

 

需要将两条select统计值一起展示，解决如下：

--缺少对应列这里为了统计用0代替(数据类型要要致),

select cid,sum(a),sum(b)
  from (SELECT cid, a.amount  a, 0  'b' from a  where a.cid = 1
            union

           select     cid, 0, b.`count` b   from b where b.cid = 1) c
group by c.cid;