How to update duplicate id?

Question

Hi friends,
I have a table EMP with duplicate IDs.
For example:
ID
100
100
200
200
200
To make it unique, I would like to concatenate at the end of each a sequence-no or rownum, like this desired output:
ID
1001
1002
2001
2002
2003
How do I write a sql to do this?
Thanks a lot,
Ms Inday

Answer 1

Hi,
crystal wrote:
Sorry Sol...the ID is varchar2 there is "-" in it like 100-001 :( is there another solution?That's exactly the kind of confusion that is avoided if you post your CREATE TABLE statement.
I think there are less than 10 duplicates each number....This does what you requested:
MERGE INTO  table_x     dst
USING  (
           SELECT  ROWID     AS r_id
        ,        ROW_NUMBER () OVER ( PARTITION BY  id
                                           ORDER BY      NULL     -- ROW_NUMBER requires ORDER BY
                          )     AS seq_num
         FROM    table_x
       )          src
ON     (src.r_id     = dst.ROWID)
WHEN MATCHED
THEN UPDATE
       SET     dst.id     = dst.id || '-' || src.seq_num
;With this technique, you can have 10, or 100, or any number of rows with the same original id. The id column must be long enough to accept the longer values. (If necessary, do an ALTER TABLE to make the column bigger before doing the MERGE.)