Probably Really Simple Solution (Where Exists in Update Statement)

Question

Right,
I have one table. In this table there are 5 fields for arguments sake:
COLUMN_ONE COLUMN_TWO COLUMN_THREE COLUMN_FOUR COLUMN_FIVE
On this table there will be duplicate records, but only column 1, column 2 and column 3 on these "duplicate" records will be the same, column 4 will differ (column 4 is not a unique identifier, but if there are duplicate records it will be different between at least 2 records). Column 5 is not yet populated, it's all null.
I need a way of updating column 5 on these duplicate records. However, I would only like to update it on one of the records and the criteria for this will be where column_4 = 'hello.'
So far I've came up with a update statement similar to the following but I don't know where to with it:
UPDATE DANS_TABLE
SET COLUMN_five = 'DUPLICATE'
WHERE EXISTS (SELECT column_one||column_two||column_three, COUNT(*)
FROM DANS_TABLE
GROUP BY column_one||column_two||column_three
HAVING ( COUNT(*) > 1 )) and column_four = 'hello';
Thanks a lot for any help!!! Very much appreciated,
Dan

Answer 1

Here is the query that updates only one duplicate row for column_five. Hope this helps..
UPDATE DANS_TABLE x1
SET COLUMN_five = 'DUPLICATE'
WHERE EXISTS
select r_id from
( select max(rowid) r_id,column_one||column_two||column_three
from DANS_TABLE t1 where exists
select str from
SELECT column_one||column_two||column_three str, COUNT(*)
FROM DANS_TABLE
GROUP BY column_one||column_two||column_three
HAVING ( COUNT(*) > 1 )
) t2 where t2.str = t1.column_one||t1.column_two||t1.column_three
) group by column_one||column_two||column_three
) x2 where x1.rowid=x2.r_id
) and column_four = 'hello';