mysql - 如何返回列中连续行与其他数据的差异 (mySQL)

Question

我正在从 mysql 表中获取一些事务数据，如下所示:

SELECT bill_no as Document_No, bill_date as Trans_Date, bill_amount as Amount, 0 as Balance
FROM bill_table
WHERE consumer_name = 'John'
UNION
SELECT receipt_no as Document_No, receipt_date as Trans_Date, -receipt_amount as Amount, 0 as Balance
FROM receipt_table
WHERE consumer_name = 'John'
ORDER BY Trans_Date

结果是这样的

+-----------+----------+------+-------+
|Document_No|Order_date|Amount|Balance|
+-----------+----------+------+-------+
|BILL58788  |2010-08-09|493   | 0     |
|BILL58789  |2010-08-10|789   | 0     |
|REC_12379  |2010-08-11|-1282 | 0     |
|BILL58788  |2010-08-12|1493  | 0     |
|BILL58788  |2010-09-01|4930  | 0     |
|REC_12380  |2010-10-02|-2000 | 0     |
+-----------+----------+------+-------+

这为我提供了约翰的所有账单和收据详细信息。所有金额都在同一列中，帐单金额为正，收据金额为负。

在最后一列“余额”中，我想要像这样动态计算的连续金额总数:

+-----------+----------+------+-------+
|Document_No|Order_date|Amount|Balance|
+-----------+----------+------+-------+
|BILL58788  |2010-08-09|493   | 493   |
|BILL58789  |2010-08-10|789   | 1282  |
|REC_12379  |2010-08-11|-1282 | 0     |
|BILL58788  |2010-08-12|1493  | 1493  |
|BILL58788  |2010-09-01|4930  | 6423  |
|REC_12380  |2010-10-02|-2000 | 4423  |
+-----------+----------+------+-------+

我知道我可以在获取数据后在 PHP 中完成此操作，但我想通过 mySQL 本身完成此操作。

这可能吗？请帮忙。 提前致谢。

Answer 1

在 MySQL 中，最简单的方法是使用变量:

select Document_No, bill_date, bill_amount, 
       (@balance := @balance + bill_amount) as balance
from ((SELECT bill_no as Document_No, bill_date as Trans_Date, bill_amount as Amount
       FROM bill_table
       WHERE consumer_name = 'John'
      )
      UNION ALL
      (SELECT receipt_no as Document_No, receipt_date as Trans_Date, -receipt_amount as Amount
      FROM receipt_table
      WHERE consumer_name = 'John'
     )
    ) t cross join
    (select @balance := 0) const
ORDER BY Trans_Date;