Question

I have the following table:

CREATE TABLE TEST(ID TINYINT NULL, COL1 CHAR(1))
INSERT INTO TEST(ID,COL1) VALUES (1,'A')
INSERT INTO TEST(ID,COL1) VALUES (2,'B')
INSERT INTO TEST(ID,COL1) VALUES (1,'A')
INSERT INTO TEST(ID,COL1) VALUES (1,'B')

INSERT INTO TEST(ID,COL1) VALUES (1,'B')
INSERT INTO TEST(ID,COL1) VALUES (2,'B')

I would like to select duplicate rows from that table. How can I select them?

I tried the following:

SELECT TEST.ID,TEST.COL1
FROM TEST WHERE TEST.ID IN
(SELECT ID
FROM TEST WHERE TEST.COL1 IN
(SELECT COL1
FROM TEST WHERE TEST.ID IN
(SELECT ID
FROM TEST
GROUP BY ID
HAVING COUNT(*) > 1)
GROUP BY COL1
HAVING COUNT(*) > 1)
GROUP BY ID
HAVING COUNT(*) > 1)

Where’s the error? What do I need to modify?

And I would like it to show as:

ID   COL1
---- ----
1    A
1    A
1    B
1    B

(4 row(s) affected)

Answer 1

Using Sql Server 2005+ and CTE you could try

;WITH Dups AS (
    SELECT *,
            ROW_NUMBER() OVER(PARTITION BY ID, Col1 ORDER BY ID, Col1) Rnum
    FROM @TEST t
)
SELECT *
FROM Dups
WHERE Rnum > 1

OR just a standard

SELECT  ID, 
        Col1,
        COUNT(1) Cnt
FROM    @TEST
GROUP BY    ID, 
            Col1
HAVING  COUNT(1) > 1

EDIT:

Display duplicate rows

SELECT  t.*
FROM    @Test t INNER JOIN
        (
            SELECT  ID,  
                    Col1, 
                    COUNT(1) Cnt 
            FROM    @TEST 
            GROUP BY    ID,  
                        Col1 
            HAVING  COUNT(1) > 1 
        ) dups  ON  t.ID = dups.ID 
                AND t.Col1 = dups.Col1