Question

我在两个表中有一些非规范化数据。它是非规范化的，因为从DepositsAndWithdrawals表（下面的第二个）我可以获得当前客户的余额，但是为了快速访问我将它保存在UserBalance表中（下面的第一个）所以我不需要将所有的操作总和全部时间：

+----+----------+---------+
| ID | Username | Balance |
+----+----------+---------+
| 1  | Alice    | 50      |
+----+----------+---------+
| 2  | Bob      | 20      |
+----+----------+---------+
| 3  | Charles  | 30      |
+----+----------+---------+

+----+------------+---------+
| ID | CustomerID | Amount  |
+----+------------+---------+
| 1  | 1          | 50      |
+----+------------+---------+
| 2  | 2          | 80      |
+----+------------+---------+
| 3  | 3          | 10      |
+----+------------+---------+
| 4  | 2          | -60     |
+----+------------+---------+
| 5  | 3          | 20      |
+----+------------+---------+

如果系统中存在竞争条件，则会出现一致性问题。因此，为了检测这些，我希望每天都有一个数据库查询来检测平衡不一致性（即SUM(amount)与balance不同时）。如何在单个SQL语句中进行这样的JOIN？

Answer 1

试试这个

SELECT A.ID As customerId, A.BALANCE, SUM(B.AMOUNT) AS REAL_BALANCE FROM A
 JOIN B on A.ID = B.customerId
GROUP BY A.ID, A.BALANCE
HAVING SUM(B.AMOUNT) <> A.BALANCE

B表是DepositsAndWithdrawals，A是UserBalance表

仅在一个SQL查询中检测非规范化数据不一致性？

1 个答案: