MySQL如何先对子组求和，然后对总和求和

Question

我的数据位于 table_1 和 table_2 中。

表_1

id  id_1 num   ids_2
1   3    33    666,777,888
2   3    333   6666,7777,8888
3   4    44    111,222,333
4   4    444   1111,2222,3333

表_2

id_2   num
111    1
222    2
333    3
1111   1
2222   2
3333   3
666    6
777    7
888    8
6666   6
7777   7
8888   8

我只知道如何通过两步来做我想做的事:

首先左连接得到:

SELECT t1.id_1, sum(t2.num) 
FROM table_1 AS t1 
LEFT JOIN table_2 AS t2 
ON FIND_IN_SET(t2.id_2, t1.ids_2) 
GROUP BY t1.id_1;

id_1 sum(t2.num)
3    6+7+8+6+7+8
4    1+2+3+1+2+3

然后再次与 table_1 LEFT JOIN 得到 sum(table_1.num)+sum(table_2.num):

id_1 sum(table_1.num)+sum(table_2.num)
3    6+7+8+6+7+8+33+333
4    1+2+3+1+2+3+44+444

我可以只用一条 SQL 来完成吗？

Answer 1

<强> Here is the SQLFIddel Demo

以下是您可以尝试的查询

SELECT A.id_1, sum(B.num)+sum(distinct A.num)
  FROM table_1 AS A 
  LEFT JOIN table_2 AS B
    on FIND_IN_SET(B.id_2, A.ids_2) 
 GROUP BY A.id_1;