How to remove duplicate records in a table?

Question

I\'ve got a table in a testing DB that someone apparently got a little too trigger-happy on when running INSERT scripts to set it up. The schema looks like this:

Answer 1

WITH Duplicates(ID , TYPE_INT, SYSTEM_VALUE, NAME, MAPPED_VALUE )
AS
(
SELECT  Min(Id)  ID  TYPE_INT, SYSTEM_VALUE, NAME, MAPPED_VALUE 
FROM T1
GROUP BY TYPE_INT, SYSTEM_VALUE, NAME, MAPPED_VALUE
HAVING Count(Id) > 1
)
DELETE FROM T1
WHERE ID IN (
SELECT T1.Id
FROM T1
INNER JOIN Duplicates
ON T1.TYPE_INT = Duplicates.TYPE_INT
AND T1.SYSTEM_VALUE = Duplicates.SYSTEM_VALUE
AND T1.NAME = Duplicates.NAME
AND T1.MAPPED_VALUE = Duplicates.MAPPED_VALUE
AND T1.Id <> Duplicates.ID
)