SQL Running Subtraction

Question

I have a result set as below:

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

query is:

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

I need to get result as in second chart. Basically I have a total of received quantity in each line and I need to show received quantity against Expected Quantity, if there is any shortage I need to show in last line.

Expected:

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

Thanks in advance.

Edited, Vession 02 ;

--    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'  

Answer 1

One part of the problem is to get the running totals of expected item qunatities. For that you'd need a way to distinguish rows with same items from each other and a rule for the order of discharging same item quantities.

For the purpose of my attempt at solving your problem I'm going to assume there's a timestamp column whose values provide the order of discharge and are unique within same item groups.

Here's the sample data definition I was testing my solution on:

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;

And here's my solution:

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

Answer 2

select a.Item, a.ExpectedQty,b.ReceivedQty, (a.ExpectedQty - b.ReceivedQty) as 'Short' from a join b on a.Item = b.Item

Answer 3

SELECT  a.ExpectedQty,
    b.ReceivedQty,
    CASE WHEN b.ReceivedQty < a.ExpectedQty
         THEN b.ReceivedQty - a.ExpectedQty
         ELSE 0
    END Short
FROM    dbo.a a
INNER JOIN dbo.b b
ON      a.ItemId = b.ItemId