SQL运行减法

我的结果集如下：

Item    ExpectedQty  ReceivedQty  Short
Item01  30           45           5
Item01  20           45           5

Item02  40           38           2

item03  50           90           10
item03  30           90           10
item03  20           90           10

查询是：

select a.Item, a.ExpectedQty,b.ReceivedQty, b.Short
from a join b on a.Item = b.Item

我需要得到第二张图表中的结果。基本上，我每行都有收到的总数量，我需要根据预期数量显示收到的数量，如果有任何短缺，我需要在最后一行显示。

预期的：

Item    ExpectedQty  ReceivedQty  Short
item01  30           30           0
item01  20           15           5

item02  40           38           2

item03  50           50           0
item03  30           30           0
item03  20           10           10

提前致谢。

编辑， 第 02 版；

--    Just a brief of business scenario is table has been created for a good receipt. 
--    So here we have good expected line with PurchaseOrder(PO) in first few line. 
--    And then we receive each expected line physically and that time these 
--    quantity may be different 
--    due to business case like quantity may damage and short quantity like that. 
--    So we maintain a status for that eg: OK, Damage, also we have to calculate
--    short quantity 
--    based on total of expected quantity of each item and total of received line.


if object_id('DEV..Temp','U') is not null
drop table Temp

CREATE TABLE Temp 
(        
ID INT IDENTITY(1,1) PRIMARY KEY CLUSTERED,        
Item VARCHAR(32),
PO VARCHAR(32) NULL,        
ExpectedQty INT NULL,
ReceivedQty INT NULL,
[STATUS] VARCHAR(32) NULL,
BoxName VARCHAR(32) NULL
)


--  Please see first few line with PO data will be the expected lines, 
--  and then rest line will be received line

INSERT INTO TEMP (Item,PO,ExpectedQty,ReceivedQty,[STATUS],BoxName)
SELECT 'ITEM01','PO-01','30',NULL,NULL,NULL UNION ALL 
SELECT 'ITEM01','PO-02','20',NULL,NULL,NULL UNION ALL 
SELECT 'ITEM02','PO-01','40',NULL,NULL,NULL UNION ALL 
SELECT 'ITEM03','PO-01','50',NULL,NULL,NULL UNION ALL 
SELECT 'ITEM03','PO-02','30',NULL,NULL,NULL UNION ALL 
SELECT 'ITEM03','PO-03','20',NULL,NULL,NULL UNION ALL 
SELECT 'ITEM04','PO-01','30',NULL,NULL,NULL UNION ALL 
SELECT 'ITEM01',NULL,NULL,'20','OK','box01' UNION ALL 
SELECT 'ITEM01',NULL,NULL,'25','OK','box02' UNION ALL 
SELECT 'ITEM01',NULL,NULL,'5','DAMAGE','box03' UNION ALL 
SELECT 'ITEM02',NULL,NULL,'38','OK','box04' UNION ALL 
SELECT 'ITEM02',NULL,NULL,'2','DAMAGE','box05' UNION ALL 
SELECT 'ITEM03',NULL,NULL,'30','OK','box06' UNION ALL 
SELECT 'ITEM03',NULL,NULL,'30','OK','box07' UNION ALL 
SELECT 'ITEM03',NULL,NULL,'30','OK','box08' UNION ALL 
SELECT 'ITEM03',NULL,NULL,'10','DAMAGE','box09' UNION ALL
SELECT 'ITEM04',NULL,NULL,'25','OK','box10' 



--  Below Table is my expected result based on above data. 
--  I need to show those data following way. 
--  So I appreciate if you can give me an appropriate query for it. 
--  Note: first row is blank and it is actually my table header. :) 

SELECT  ''as'ITEM', ''as'PO#', ''as'ExpectedQty',''as'ReceivedQty',
''as'DamageQty' ,''as'ShortQty' UNION ALL 

SELECT 'ITEM01','PO-01','30','30','0' ,'0'  UNION ALL 
SELECT 'ITEM01','PO-02','20','15','5' ,'0'  UNION ALL 
SELECT 'ITEM02','PO-01','40','38','2' ,'0'  UNION ALL 
SELECT 'ITEM03','PO-01','50','50','0' ,'0'  UNION ALL 
SELECT 'ITEM03','PO-02','30','30','0' ,'0'  UNION ALL 
SELECT 'ITEM03','PO-03','20','10','10','0' UNION ALL 
SELECT 'ITEM04','PO-01','30','25','0' ,'5'  

问题的一部分是获取预期项目数量的运行总计。为此，您需要一种方法来区分具有相同项目的行，以及卸载相同项目数量的顺序的规则。

为了尝试解决您的问题，我将假设有一个时间戳列，其值提供放电顺序并且在同一项目组中是唯一的。

这是我正在测试我的解决方案的示例数据定义：

CREATE TABLE TableA (Item varchar(50), ExpectedQty int, Timestamp int);
INSERT INTO TableA
SELECT 'Item01', 30, 1 UNION ALL
SELECT 'Item01', 20, 2 UNION ALL
SELECT 'Item02', 40, 1 UNION ALL
SELECT 'item03', 50, 1 UNION ALL
SELECT 'item03', 30, 2 UNION ALL
SELECT 'item03', 20, 3;

CREATE TABLE TableB (Item varchar(50), ReceivedQty int);
INSERT INTO TableB
SELECT 'Item01', 45 UNION ALL
SELECT 'Item02', 38 UNION ALL
SELECT 'item03', 90;

这是我的解决方案：

SELECT
  Item,
  ExpectedQty,
  ReceivedQty = CASE
    WHEN RemainderQty >= 0 THEN ExpectedQty
    WHEN RemainderQty < -ExpectedQty THEN 0
    ELSE RemainderQty + ExpectedQty
  END,
  Short = CASE
    WHEN RemainderQty >= 0 THEN 0
    WHEN RemainderQty < -ExpectedQty THEN ExpectedQty
    ELSE ABS(RemainderQty)
  END
FROM (
  SELECT
    a.Item,
    a.ExpectedQty,
    RemainderQty = b.ReceivedQty - a.RunningTotalQty
  FROM (
    SELECT
      a.Item,
      a.Timestamp,
      a.ExpectedQty,
      RunningTotalQty = SUM(a2.ExpectedQty)
    FROM TableA a
      INNER JOIN TableA a AS a2 ON a.Item = a2.Item AND a.Timestamp >= a2.Timestamp
    GROUP BY
      a.Item,
      a.Timestamp,
      a.ExpectedQty
  ) a
    INNER JOIN TableB b ON a.Item = b.Item
) s