如何返回相繼排差異與其他數據（MySQL的）一列

Question

我從一個MySQL表中讀取一些事務性的數據是這樣的：

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 

導致這樣的事情

 
+-----------+----------+------+-------+ 
|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  | 
+-----------+----------+------+-------+ 

這給我所有的賬單&約翰的收據細節。所有金額在同一欄中，帳單金額爲正數&收據金額爲負數。

在最後一列「平衡」，我希望有一個總的連續大量像這樣的，動態計算：

 
+-----------+----------+------+-------+ 
|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PHP中獲取數據後，做到這一點，但我想這樣做mySQL本身。

可能嗎？請幫忙。 在此先感謝。

Answer 1

在MySQL中，要做到這一點最簡單的方法是使用變量：

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;