Delete duplicate rows in SQL Server and Oracle

 SQL SERVER

DELETE FROM Table1 WHERE ID NOT IN
(  SELECT MAX(ID) FROM Table1
GROUP BY DuplicateColumn1, DuplicateColumn2, DuplicateColumn3 )






WITH CTE (COl1,Col2, DuplicateCount)
AS
(
SELECT COl1,Col2,
ROW_NUMBER() OVER(PARTITION BY COl1,Col2 ORDER BY Col1) AS DuplicateCount
FROM TableName
)
DELETE
FROM CTE
WHERE DuplicateCount > 1
GO



AND In ORACLE 
 



DELETE FROM TABLE1
WHERE ROWID NOT IN (SELECT   MIN (ROWID)
FROM TABLE1
GROUP BY COLUMN1, COLUMN2, COLUMN3, COLUMN4);