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T-SQL Query | [Finding Previous Value Puzzle] – Write a query which will extract the previous value from the currentQuota for each row.

Input

BusinessEntityID SalesYear CurrentQuota
275 2005 367000
275 2005 556000
275 2006 502000
275 2006 550000
275 2006 1429000
275 2006 1324000

Output ..> We need to extract the last value from the currentQuota ( Last Column )

BusinessEntityID SalesYear CurrentQuota lagCurrentData
275 2005 367000 0
275 2005 556000 367000
275 2006 502000 556000
275 2006 550000 502000
275 2006 1429000 550000
275 2006 1324000 1429000

Rules/Restrictions
◾The solution should be should use “SELECT” statement or “CTE”.
◾Send your solution to pawankkmr@gmail.com
◾Do not post you solution in comments section

Script Use the below script to generate the source table and fill them up with the sample data.



--So we first create the table

CREATE TABLE lag
(
BusinessEntityID INT
,SalesYear   INT
,CurrentQuota  DECIMAL(20,4)
)
GO

INSERT INTO lag
SELECT 275 , 2005 , '367000.00'
UNION ALL
SELECT 275 , 2005 , '556000.00'
UNION ALL
SELECT 275 , 2006 , '502000.00'
UNION ALL
SELECT 275 , 2006 , '550000.00'
UNION ALL
SELECT 275 , 2006 , '1429000.00'
UNION ALL
SELECT 275 , 2006 ,  '1324000.00'

Update May 14 | Solution


--

/************   SOLUTION 1    | Pawan Kumar Khowal     ****************/

;WITH CTE AS
( 
	SELECT  BusinessEntityID ,SalesYear ,CurrentQuota
	, ROW_NUMBER() OVER (ORDER BY BusinessEntityID ) AS ID
	FROM lag
)
SELECT c.BusinessEntityID ,c.SalesYear , c.CurrentQuota
	, ISNULL((SELECT TOP 1 d.CurrentQuota FROM CTE d WHERE c.ID > d.ID ORDER BY ID DESC ),0) lagCurrentData
FROM CTE c


/************   SOLUTION 2    | Pawan Kumar Khowal     ****************/

;WITH CTE AS
(
 SELECT BusinessEntityID ,SalesYear ,CurrentQuota ,ROW_NUMBER()OVER (ORDERBY BusinessEntityID )AS ID
 FROM lag
)
SELECT c.Id ,c.BusinessEntityID ,c.SalesYear , c.CurrentQuota,ISNULL(d.CurrentQuota,0) lagCurrentData
FROM CTE c LEFTOUTERJOIN CTE d ON c.ID =(d.ID+1)


--

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