Question

我有三张桌子：

TableA

+-------+--------+--------+
| id_a  | name   | total  |
+-------+--------+--------+
|    1  | Andrew |        |
|    2  | Jhon   |        |
+-------+--------+--------+

TableB

+-------+--------+--------+--------+
| id_b  | id_a   | amount | id_c   |
+-------+--------+--------+--------+
|    1  | 1      |    5   | 1      |
|    2  | 1      |    1   | 2      |
+-------+--------+--------+--------+

TableC

+-------+--------+
| id_c  | status |
+-------+--------+
|    1  | 1      |
|    2  | 0      |
+-------+--------+

所以我需要做的是计算TableB中的总金额，其中id_a =（1或我发布的id）AND id_c的状态是1或0，并将其设置为总列中的TableA，我在TableA中的字段total上方发布的表格中的数据，其中id_a = 1将包含6值。

我试图通过这种方式进入我的查询：

UPDATE TableA SET total=(SELECT SUM(amount) as sum FROM TableB WHERE id_a = 1 GROUP BY(sum))

但这是错误的（我认为）。怎么会对此有好的疑问？

Answer 1

您可以在内部INNER JOIN中的TableB和TableC之间使用SELECT。

UPDATE TableA SET
    total=(
        SELECT SUM(amount) FROM TableB
                           INNER JOIN TableC ON TableB.id_c = TableC.id_c
        WHERE id_a = 1 AND (status = 1 OR status = 0)
        GROUP BY id_a
    )
WHERE id_a = 1

Answer 2

试试这个

   UPDATE TableA SET total=(SELECT SUM(amount)  FROM TableB WHERE id_a = 1)

如何从第一个表到另外两个表更新记录？

2 个答案: