declare @i table (Col1 varchar(32),Col2 varchar(32))
insert into @i SELECT
'A','Peter' union all SELECT 
'B','Nelson' union all SELECT 
'C','USA' union all SELECT 
'D','29' union all SELECT 
'A','Mary' union all SELECT 
'B','Kumar' union all SELECT 
'C','USA' union all SELECT 
'd','25'

DROP TABLE #temp
DROP TABLE #temp1

SELECT ROW_NUMBER() OVER(PARTITION BY COL1 ORDER BY col1) AS rid,* INTO #temp FROM @i

SELECT ROW_NUMBER()over(PARTITION BY rid ORDER BY col1,col2,col3,col4) AS id,* INTO #temp1 FROM
(SELECT t.rid,
CASE WHEN t.col1  = 'a' THEN  t.col2
	 WHEN t.col1  = 'a' THEN  t.col2  END col1,
CASE WHEN t1.col1 = 'b' THEN  t1.col2
	 WHEN t1.col1 = 'b' THEN  t1.col2 END col2,
CASE WHEN t2.col1 = 'c' THEN  t2.col2
	 WHEN t2.col1 = 'c' THEN  t2.col2 END col3,
CASE WHEN t3.col1 = 'd' THEN  t3.col2
	 WHEN t3.col1 = 'd' THEN  t3.col2 END col4
FROM #temp t
LEFT JOIN #temp t1 ON t1.rid = t.rid 
LEFT JOIN #temp t2 ON t2.rid = t.rid 
LEFT JOIN #temp t3 ON t3.rid = t.rid )s

DECLARE @maxid  INT
SELECT @maxid = id FROM #temp1
SELECT col1,col2,col3,col4 FROM #temp1 where id = @maxid