Compare dates between 2 different rows and columns

You can use one of the below methods

if sql 2012 or above

SELECT *
FROM
(
SELECT *,LEAD(Effective_Date,1) OVER (PARTITION BY Customer_ID ORDER BY ROWID) AS NxtDate
FROM Table
)t
WHERE NxtDate < Discontinue_Date

if earlier version

;With CTE
AS
(
SELECT ROW_NUMBER() OVER(PARTITION BY Customer_ID ORDER BY ROWID) AS Seq,*
FROM Test
)

SELECT c1.ROWID , 
c1.Customer_ID  ,  
c1.PART_ID ,  
c1.Effective_Date , 
c1.Discontinue_Date
FROM CTE c1
INNER JOIN CtE c2
ON c2.Seq = c1.Seq + 1
AND c2.Customer_ID = c1.Customer_ID
WHERE c2.Effective_Date < c1.Discontinue_Date

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Visakh

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