Faced with this problem, any idea how to go about it?
SELECT * FROM (
(SELECT COL1, COL2, MAX(COL3),
ROWNUMBER() OVER (ORDER BY COL1) AS ROW_NEXT
WHERE COL1 = 'A'
GROUP BY COL1, COL2)
UNION
(SELECT COL1, COL2, COL3,
ROWNUMBER() OVER (ORDER BY COL1) AS ROW_NEXT
WHERE COL1 != 'A'...