Using UNION in Oracle

Union will combine two sets of data, see example below :)

select a.KOD_JENIS, a.NAMA_JENIS, count(b.KOD_JENIS)
from ptype a, pmain b
where a.KOD_JENIS = b.KOD_JENIS
group by a.KOD_JENIS, a.NAMA_JENIS
union
select '-', 'No Data', count(*)
from pmain b
where b.kod_jenis is null