SELECT *
FROM (
SELECT z.*, p.Zone_NO AS p_Zone_NO
FROM CDB_ZONE z, CDB_PSTATION p
WHERE z.Zone_NO = p.Zone_NO(+)) a
WHERE p_Zone_NO IS NULL
FROM (
SELECT z.*, p.Zone_NO AS p_Zone_NO
FROM CDB_ZONE z, CDB_PSTATION p
WHERE z.Zone_NO = p.Zone_NO(+)) a
WHERE p_Zone_NO IS NULL
cdb_pstation.zone_no= cdb_zone.cdb_zone )
cdb_pstation.zone_no= cdb_zone.cdb_zone )
select *
from CDB_PSTATION a,CDB_ZONE b
where a.Zone_NO(+)=b.Zone_NO
and a.Zone_NO is null