MySQL的垂直水平和與垂直總和在同一時間

Question

我有2個表，其由一組數據如下的和我想要得到的結果，作爲其結果將有一個計算在現場balance：

我我卡在balance字段，我如何獲得balance正在運行？

tblIn

in_date | code | in_qty 
-----------|---------|--------- 
2016-04-01 | aaa  | 100 
2016-04-03 | aaa  | 200 
2016-04-06 | aaa  | 400 

tblOut

out_date | code | out_qty 
-----------|---------|--------- 
2016-04-02 | aaa  | 100 
2016-04-08 | aaa  | 400 

RESULT

date  | code | in_qty | out_qty | balance 
-----------|---------|----------|----------|--------- 
2016-04-01 | aaa  | 100  | 0  | 100 
2016-04-02 | aaa  | 0  | 100  | 0 
2016-04-03 | aaa  | 200  | 0  | 200 
2016-04-06 | aaa  | 400  | 0  | 600 
2016-04-08 | aaa  | 0  | 400  | 200 

QUE RY

SELECT 
    t.date, 
    t. CODE, 
    t.in_qty, 
    t.out_qty 
FROM 
    (
     SELECT 
      date, 
      in_qty, 
      0 AS out_qty 
    FROM tblIn 
     UNION ALL 
     SELECT 
      date, 
      0 AS in_qty, 
      out_qty 
     FROM tblOut 
    ) t 
ORDER BY date ASC 

Answer 1

你可以試試這個查詢：

SELECT 
t.*, 
@prevBalance := (t.in_qty - t.out_qty) + IFNULL(@prevBalance,0) AS balance 
FROM 
(
    SELECT 
     in_date date, 
     code, 
     in_qty, 
     0 AS out_qty 
    FROM tblin 

    UNION 

    SELECT 
     out_date, 
     code, 
     0, 
     out_qty 
    FROM tblout 
) t , (SELECT @prevBalance := NULL) var 
ORDER BY t.date; 

SQL FIDDLE DEMO

注：

如果初始化@prevBalance與zero然後IFNULL(@prevBalance,0)變量不再需要。

所以如果你使用這樣的：

(SELECT @prevBalance := 0) var

然後更改餘額列象下面這樣：

@prevBalance := (t.in_qty - t.out_qty) + @prevBalance

Answer 2

你通常會使用全外與日期作爲共同的因素加入，但MySQL不會允許全外連接。

有一個變通的鏈接下方

http://www.xaprb.com/blog/2006/05/26/how-to-write-full-outer-join-in-mysql/

指定ON狀態的日期。

Answer 3

嗯，讓我們像這樣做;）

CREATE TABLE IF NOT EXISTS `tblIn` (
    `in_date` date DEFAULT NULL, 
    `code` char(50) DEFAULT NULL, 
    `in_qty` int(11) DEFAULT NULL 
) ENGINE=InnoDB DEFAULT CHARSET=utf8; 


CREATE TABLE IF NOT EXISTS `tblOut` (
    `out_date` date DEFAULT NULL, 
    `code` char(50) DEFAULT NULL, 
    `out_qty` int(11) DEFAULT NULL 
) ENGINE=InnoDB DEFAULT CHARSET=utf8; 

然後嘗試這個，也許工作;）

SELECT TMP.date, TMP.code, TMP.in_qty, TMP.out_qty, @BALANCE:=@BALANCE + TMP.BALANCE AS balance 
FROM (
    SELECT out_date as date, 
      code, 
      0 as in_qty, 
      out_qty, 
      0-out_qty as balance 
    FROM tblOut 
    UNION 
    SELECT in_date as date, 
      code, 
      in_qty, 
      0 as out_qty, 
      in_qty as balance 
    FROM tblIn) TMP, 
    (SELECT @BALANCE:=0) B 
ORDER BY TMP.date