Concatenation of row data into a single row

Question

Hi,
I have table which has the data in the following way.
  col1          col2    col3
  a             1       one
  a             2       two
  a             3       three
  b             1       dfdf
  b             2       sfdhh
  c             1       zgdhi want data in the following way.
  col1          col2    col3
  a             1,2,3   one,two,three
  b             1,2     dfdf,sfdhh
  c             1       zgdhCan any body help me.
Thanks in advance

Answer 1

may be this will work
WITH tab AS
      (SELECT 'A' col1,1 col2, 'one' col3 FROM dual
       UNION ALL
       SELECT 'A' col1,2 col2, 'two' col3 FROM dual
       UNION ALL
       SELECT 'A' col1,3 col2, 'three' col3 FROM dual
       union all
       SELECT 'B' col1,1 col2, 'abc' col3 FROM dual
       UNION ALL
       SELECT 'B' col1,2 col2, 'defg' col3 FROM dual
       UNION ALL
       SELECT 'C' col1,1 col2, 'hijcol' FROM dual
       union all
       SELECT 'C' col1,2 col2,'klm' col3 FROM dual
       SELECT col1
     , ltrim(MAX(SYS_CONNECT_BY_PATH(col2,','))
       KEEP (DENSE_RANK LAST ORDER BY curr),',') AS col2,
       ltrim(MAX(SYS_CONNECT_BY_PATH(col3,','))
       KEEP (DENSE_RANK LAST ORDER BY curr),',')as col3
FROM   ( SELECT col1
              , col2,col3
              , ROW_NUMBER() OVER (PARTITION BY col1 ORDER BY col2) AS curr
              , ROW_NUMBER() OVER (PARTITION BY col1 ORDER BY col2) -1 AS prev
         FROM   tab )
GROUP BY col1
CONNECT BY prev = PRIOR curr AND col1 = PRIOR col1
START WITH curr = 1;
COL1     COL2     COL3
A     1,2,3     one,two,three
B     1,2     abc,defg
C     1,2     hijcol,klm