mysql - 使用条件选择和求和选择不同的行

Question

我有一个 MySQL 选择，但无法使其工作。我的简化 order 表如下所示:

+----+------------+----------------+-------+----------------+
| id | partner_id | personal_price | price | modified_price |
+----+------------+----------------+-------+----------------+
|  1 |          1 |            500 |   900 | NULL           |
|  2 |          1 |            700 |  1100 | 1400           |
|  3 |          2 |            400 |   800 | NULL           |
+----+------------+----------------+-------+----------------+

如果设置了，total_price 应该是 modified_price，如果没有设置，则应该是 price。我还想区分合作伙伴的行，汇总 total_price 和 personal_price 并将差异计算为 partner_price。

结果应该如下所示:

+------------+-------------+----------------+---------------+
| partner_id | total_price | personal_price | partner_price |
+------------+-------------+----------------+---------------+
|          1 |        2300 |           1200 |          1100 |
|          2 |         800 |            400 |           400 |
+------------+-------------+----------------+---------------+

到目前为止，代码不起作用的是:

SELECT
  DISTINCT partner_id,
  SUM ( CASE WHEN price_modified IS NULL 
    THEN price 
    ELSE price_modified END ) as total_price,
  SUM ( presonal_price ),
  total_price - personal_price as parnter_price
  FROM orders

感谢您的帮助

Answer 1

您需要按partner_id分组并且不使用不同的:

select
  partner_id,
  sum(coalesce(modified_price, price)) total_price,
  sum(personal_price) personal_price,
  sum(coalesce(modified_price, price) - personal_price) partner_price
from orders
group by partner_id

请参阅demo .
结果:

| partner_id | total_price | personal_price | partner_price |
| ---------- | ----------- | -------------- | ------------- |
| 1          | 2300        | 1200           | 1100          |
| 2          | 800         | 400            | 400           |