CREATE TABLE Table1 (IDCol char(1) ,Col1 Int ,Col2 Int)
GO 

INSERT INTO Table1 (IDCol, Col1, Col2)
SELECT 'A', 1, 2 UNION ALL 
SELECT 'B', 1, 2 UNION ALL 
SELECT 'A', 1, 3 UNION ALL 
SELECT 'C', 2, 1 UNION ALL 
SELECT 'B', 1, 3 UNION ALL 
SELECT 'A', 2, 4
GO

SELECT IDCol, Col1, Col2 FROM Table1 o
 WHERE IDCol  In ('A','B')
   AND NOT EXISTS (SELECT 1 FROM Table1 a INNER JOIN Table1 b 
		       ON a.Col1 = b.Col1 AND a.Col2 = b.Col2
		    WHERE a.IDCol = 'A' And b.IDCol = 'B'
		      AND (    o.IDCol = a.IDCol AND o.Col1 = a.Col1  AND o.Col2 = a.Col2
			   OR  o.IDCol = b.IDCol AND o.Col1 = b.Col1  AND o.Col2 = b.Col2)
)
GO

DROP TABLE Table1
GO

SELECT * FROM T T2
WHERE Col2 NOT IN
  (SELECT Col2 FROM T T1
      WHERE T2.Col1 = t1.Col1 AND ID = 'B') AND ID = 'A'

SELECT * FROM T
WHERE ID IN ('A', 'B') AND Col2 NOT IN
        (SELECT Col2 FROM T T1
      WHERE T.Col1 = t1.Col1 AND T.ID <> T1.ID)