Question

这是我的表：

+------+---------+------+------+
| Name | orderNo  Total   used |
+------+---------+------+------+
| Row1 |    1    |   10 |    2 |
| Row2 |    1    |    8 |    1 |
| Row3 |    1    |    7 |    3 |
| Row4 |    2    |   12 |    8 |
+------+---------+-----+-------+

这就是我想要的：

+------+---------+------+------+---------+
| Name | orderNo  Total   used   balance |
+------+---------+------+------+---------+
| Row1 |    1    |   10 |    2 |  8      |
| Row2 |    1    |    8 |    1 |  7      |
| Row3 |    1    |    7 |    3 |  4      |
| Row4 |    2    |   12 |    8 |  4      |
+------+---------+-----+-------+---------+

我从两列的差值计算余额。但无法在总列的下一行中设置余额值。任何人都可以为我提供解决方案吗？

Answer 1

我不知道你在哪里遇到问题

SELECT Name, orderNo,  Total ,  used, (Total - used) as balanced
FROM table

如果您想添加强烈不推荐的列：

ALTER TABLE table_name
ADD balanced INT;

然后更新表格：

UPDATE table a
INNER JOIN (SELECT Name, orderNo, Total, used, (Total - used) AS balanced
            FROM table) b ON b.Name = a.Name AND b.orderNo = a.orderNo
SET a.balanced = b.balanced

显示mysql中相同orderNo的下一行总列中前一行的平衡列数据

1 个答案: