Procedure or function returning a result set

I have a query like this :
SELECT * FROM ETABLISSEMENT
WHERE NUM_ETAB IN(
SELECT NUM_ETAB FROM
(SELECT

SUM(DECODE(ID_ANNEE,1998,BB)) AS N ,
SUM(DECODE(ID_ANNEE,1999,BB)) AS N1 ,
NUM_ETAB
FROM DONNEES_TP
WHERE ID_ANNEE=1998 OR ID_ANNEE=1999
GROUP BY NUM_ETAB)
WHERE
((N IS NOT NULL AND N1 IS NULL)

OR ((N1-N)/N)<0.5))

But I would like not to hard code 1998,1999 and 0.5 but send them as params How can I do ? Received on Mon Mar 24 2003 - 10:06:15 CST