Slet duplikerede registreringer med originale

Da du bruger SQL Server 2005+, kan du bruge CTE til at udføre dette:

;WITH cte AS 
(
  SELECT ROW_NUMBER() OVER (PARTITION BY Col1, Col2, Col3  ORDER BY (SELECT 0)) RN
  FROM  yourtable
)
DELETE FROM cte
WHERE RN > 1