Question

我正在学习使用MySQL，因此我尝试进行简单的库存管理。如果我删除发票，我怎么能不只是从发票表和invoiceItemTable中删除，而是更新＆＃34;金额＆＃34;在我的库存表中右侧存储的减法值列？因为如果我想做

SUM(inventory.amount) - SUM(SELECT amount FROM InvoiceItemTable WHERE invoice_id = 1 
    GROUP BY Product_id)

这将失败，因为子查询有超过1行。下面你可以看到我的数据库结构。

InvoceTable
+---+----------------+----------+
|ID | invoice_number | Store_id |
+---+----------------+----------+
| 1 | 1234           | 1        |
+---+----------------+----------+

InvoiceItemTable
+---+----------------+------------+---------+
|ID | invoice_id     | Product_id | Amount  |
+---+----------------+------------+---------+
| 1 | 1              | 1          | 5       |
+---+----------------+------------+---------+
| 2 | 1              | 1          | 5       |
+---+----------------+------------+---------+
| 3 | 2              | 1          | 10      |
+---+----------------+------------+---------+

Inventory
+---+----------------+---------+----------+
|ID | Product_id     | Amount  | Store_id |
+---+----------------+---------+----------+
| 1 | 1              | 15      | 1        |
+---+----------------+---------+----------+
| 2 | 2              | 15      | 1        |
+---+----------------+---------+----------+
| 3 | 2              | 15      | 2        |
+---+----------------+---------+----------+

更新查询后的期望：

InvoceTable
+---+----------------+----------+
|ID | invoice_number | Store_id |
+---+----------------+----------+
|   |                |          |
+---+----------------+----------+

InvoiceItemTable
+---+----------------+------------+---------+
|ID | invoice_id     | Product_id | Amount  |
+---+----------------+------------+---------+
| 3 | 2              | 1          | 10      |
+---+----------------+------------+---------+

Inventory
+---+----------------+---------+----------+
|ID | Product_id     | Amount  | Store_id |
+---+----------------+---------+----------+
| 1 | 1              |  5      | 1        |
+---+----------------+---------+----------+
| 2 | 2              |  5      | 1        |
+---+----------------+---------+----------+
| 3 | 2              | 15      | 2        |
+---+----------------+---------+----------+

Answer 1

你需要在子查询中使用sum：

select SUM(inventory.amount) - (SELECT SUM(amount) FROM InvoiceItemTable WHERE invoice_id = 1 GROUP BY Product_id) 
from inventory

检查sqlfiddle您的数据库方案和正在运行的查询。

此查询应根据invoiceitemtable表减少Inventory表的amount列：

update Inventory set Amount = Amount - (SELECT SUM(amount) FROM InvoiceItemTable WHERE invoice_id = 1 AND Product_id = Inventory.Product_id  GROUP BY Product_id)

Answer 2

SUM(inventory.amount) - (SELECT SUM(amount) FROM InvoiceItemTable WHERE invoice_id = 1 GROUP BY Product_id)

删除行后更新列

2 个答案: