SQL Server: select newest rows who's sum matches a value - sql

Question

Here is a table...
ID QTY DATE CURRENT_STOCK
----------------------------------
1 1 Jan 30
2 1 Feb 30
3 2 Mar 30
4 6 Apr 30
5 8 May 30
6 21 Jun 30
I need to return the newest rows whose summed qty equal or exceed the current stock level, excluding any additional rows once this total has been reached, so I am expecting to see just these rows...
ID QTY DATE CURRENT_STOCK
----------------------------------
4 6 Apr 30
5 8 May 30
6 21 Jun 30
I am assuming I need a CTE (Common Table Expression) and have looked at this question but cannot see how to translate that to my requirement.
Help!?

Answer 1

Declare #YourTable table (ID int,QTY int,DATE varchar(25), CURRENT_STOCK int)
Insert Into #YourTable values
(1 ,1 ,'Jan' ,30),
(2 ,1 ,'Feb' ,30),
(3 ,2 ,'Mar' ,30),
(4 ,6 ,'Apr' ,30),
(5 ,8 ,'May' ,30),
(6 ,21 ,'Jun' ,30)
Select A.*
From #YourTable A
Where ID>= (
Select LastID=max(ID)
From #YourTable A
Cross Apply (Select RT = sum(Qty) from #YourTable where ID>=A.ID) B
Where B.RT>=CURRENT_STOCK
)
Returns
ID QTY DATE CURRENT_STOCK
4 6 Apr 30
5 8 May 30
6 21 Jun 30

Answer 2

One way to do it with your provided data set
if object_id('tempdb..#Test') is not null drop table #Test
create table #Test (ID int, QTY int, Date_Month nvarchar(5), CURRENT_STOCK int)
insert into #Test (ID, QTY, Date_Month, CURRENT_STOCK)
values
(1, 1, 'Jan', 30),
(2, 1, 'Feb', 30),
(3, 2, 'Mar', 30),
(4, 6, 'Apr', 30),
(5, 8, 'May', 30),
(6, 21, 'Jun', 30)
if object_id('tempdb..#Finish') is not null drop table #Finish
create table #Finish (ID int, QTY int, Date_Month nvarchar(5), CURRENT_STOCK int)
declare #rows int = (select MAX(ID) from #Test)
declare #stock int = (select MAX(CURRENT_STOCK) from #Test)
declare #i int = 1
declare #Sum int = 0
while #rows > #i
BEGIN
select #Sum = #Sum + QTY from #Test where ID = #rows
IF (#SUM >= #stock)
BEGIN
set #i = #rows + 1 -- to exit loop
END
insert into #Finish (ID, QTY, Date_Month, CURRENT_STOCK)
select ID, QTY, Date_Month, CURRENT_STOCK from #Test where ID = #rows
set #rows = #rows - 1
END
select * from #Finish

Answer 3

Setup Test Data
-- Setup test data
CREATE TABLE #Stock
([ID] int, [QTY] int, [DATE] varchar(3), [CURRENT_STOCK] int)
;
INSERT INTO #Stock
([ID], [QTY], [DATE], [CURRENT_STOCK])
VALUES
(1, 1, 'Jan', 30),
(2, 1, 'Feb', 30),
(3, 2, 'Mar', 30),
(4, 6, 'Apr', 30),
(5, 8, 'May', 30),
(6, 21, 'Jun', 30)
;
Solution for SQL Server 2012+
If you have a more recent version of SQL server which supports full window function syntax, you can do it look this:
-- Calculate a running total of qty by Id descending
;WITH stock AS (
SELECT *
-- This calculates the SUM over a 'window' of rows based on the first
-- row in the result set through the current row, as specified by the
-- ORDER BY clause
,SUM(qty) OVER(ORDER BY Id DESC
ROWS BETWEEN UNBOUNDED PRECEDING
AND CURRENT ROW) AS TotalQty
FROM #Stock
),
-- Identify first row in mininum set that matches or exceeds CURRENT_STOCK
first_in_set AS (
SELECT TOP 1 *
FROM stock
WHERE TotalQty >= CURRENT_STOCK
)
-- Fetch matching set
SELECT *
FROM #stock
WHERE Id >= (SELECT Id FROM first_in_set)
Solution for SQL Server 2008
For SQL Server 2008, which only has basic support for window functions, you can calculate the running total using CROSS APPLY:
-- Calculate a running total of qty by Id descending
;WITH stock AS (
SELECT *
-- This window function causes the results of this query
-- to be sorted in descending order by Id
,ROW_NUMBER() OVER(ORDER BY Id DESC) AS sort_order
FROM #Stock s1
-- CROSS APPLY 'applies' the query (or UDF) to every row in a result set
-- This CROSS APPLY query produces a 'running total'
CROSS APPLY (
SELECT SUM(Qty) AS TotalQty
FROM #Stock s2
WHERE s2.Id >= s1.id
) total_calc
WHERE TotalQty >= s1.CURRENT_STOCK
),
-- Identify first row in mininum set that matches or exceeds CURRENT_STOCK
first_in_set AS (
SELECT TOP 1 Id
FROM stock
WHERE sort_order = 1
)
-- Fetch matching set
SELECT *
FROM #stock
WHERE Id >= (SELECT Id
FROM first_in_set)