SELECT Delegate.DelegateID, Delegate.FirstName, Delegate.LastName FROM Delegate INNER JOIN (SELECT FirstName, LastName FROM Delegate GROUP BY FirstName, LastName HAVING Count(DelegateID) > 1 ) AS Duplicates ON Delegate.FirstName = Duplicates.FirstName AND Delegate.LastName = Duplicates.LastName
DELETE FROM Delegate WHERE DelegateID = ANY ( SELECT DupDels.DelegateID FROM DupDels LEFT JOIN (SELECT Min(DelegateID) AS DelegateID, FirstName, LastName FROM DupDels GROUP BY FirstName, LastName) AS FirstDup ON DupDels.DelegateID = FirstDup.DelegateID WHERE FirstDup.DelegateID IS NULL )
This is general discussion. You should translate it to your case by yourself.
CREATE TABLE Dups ( ID INT IDENTITY(1,1) PRIMARY KEY, A VARCHAR(30), B VARCHAR(30), C VARCHAR(30) ) go INSERT INTO Dups(A,B,C) VALUES ('hi','there','all') INSERT INTO Dups(A,B,C) VALUES ('hi','there','all') INSERT INTO Dups(A,B,C) VALUES ('bye','from','me') INSERT INTO Dups(A,B,C) VALUES ('repeated','three','times') INSERT INTO Dups(A,B,C) VALUES ('repeated','three','times') INSERT INTO Dups(A,B,C) VALUES ('repeated','three','times') -- Duplicate rows - one from each group SELECT * FROM Dups T WHERE ID > ( SELECT MAX(ID) FROM Dups I WHERE I.A = T.A AND I.B = T.B AND I.C = T.C AND I.ID <> T.ID ) -- Non-duplicated view - one row from each group SELECT * FROM Dups T WHERE ID >= ALL ( SELECT ID FROM Dups I WHERE I.A = T.A AND I.B = T.B AND I.C = T.C ) -- Rows to be deleted - usefull for COUNT(*) and DELETE SELECT * FROM Dups T WHERE ID < ( SELECT MAX(ID) FROM Dups I WHERE I.A = T.A AND I.B = T.B AND I.C = T.C AND I.ID <> T.ID ) -- Delete the duplicates DELETE Dups WHERE ID < ( SELECT MAX(ID) FROM Dups I WHERE I.A = Dups.A AND I.B = Dups.B AND I.C = Dups.C AND I.ID <> Dups.ID )
file: /Techref/language/sql/tsqldups.htm, 3KB, , updated: 2016/12/9 14:58, local time: 2024/12/23 18:46,
owner: JMN-EFP-786,
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