Question

table1结构和样本数据

+----+-------------+----------+------+-------+
| ID | DESCRIPTION | QUANTITY | EACH | PRICE |
+----+-------------+----------+------+-------+
| 1  | Product 1   |     1    |  12  | 1*12  |
| 2  | Product 2   |     2    |   3  | 2* 3  |
| 3  | Prodcut 3   |   NULL   |   3  |       |
| 4  | Product 1   |     2    |  10  | 2*10  |
| 5  | Product 3   |   NULL   |   7  |       |
+----+-------------+----------+------+-------+

MySQL查询：

SELECT
  DESCRIPTION,
  QUANTITY,
  EACH,
  COALESCE(QUANTITY, 1) * EACH AS PRICE
FROM table1
GROUP BY DESCRIPTION

如何为 PRICE 列和 GROUP BY DESCRIPTION 列进行 SUM ？我不想使用UPDATE，因为我无法更改table1中的值。

Answer 1

那么为什么你不能在选择列表中添加SUM(COALESCE(QUANTITY, 1) * EACH) AS PRICETOTAL。

Answer 2

SELECT
    DESCRIPTION,
    SUM(COALESCE(QUANTITY,1)*each) as 'Price'
FROM table1
GROUP BY DESCRIPTION


returns 
DESCRIPTION Price
Product 1   32
Product 2   6
Product 3   10

来自AS列的MySQL SUM和GROUP BY

2 个答案: