Try this query, without unique index/constraint -
Query:
DECLARE @temp TABLE
(
Col1 VARCHAR(10)
, Col2 VARCHAR(10)
, Col3 VARCHAR(10)
, Col4 VARCHAR(10)
)
INSERT INTO @temp (Col1, Col2, Col3, Col4)
VALUES
('1', '1', '1', '1'),
('11', '2', '3', '44'),
('111', '2', '3', '444'),
('1111', '3', '3', '3')
SELECT
Col1 = MIN(Col1)
, Col2
, Col3
, Col4 = MIN(Col4)
FROM @temp
GROUP BY
Col2
, Col3
Output:
Col1 Col2 Col3 Col4
---------- ---------- ---------- ----------
1 1 1 1
11 2 3 44
1111 3 3 3