select
      a.rjcode,
      a.rcode,
      d.code1nm aptgu,
      e.code1nm aptname,
      f.code1nm giro,
      g.code1nm bunki,
      h.code1nm rkita
from  dokja a, media b, dokcod d , dokcod e , dokcod f , dokcod g , dokcod h
where    a.rjcode = '120630'
and      a.rjcode = b.rjcode
and      a.rcode = '00318'
and      a.rcode = b.rcode
and      (d.code = '04' and a.raptgu = d.code1)
and      (e.code = '02' and a.rapt = e.code1)
and      (f.code = '06' and a.rgiroflag = f.code1)
and      (g.code = '14' and a.rbun = g.code1)
and      ((h.code = '13' and a.rkita = h.code1 ) or (a.rkita is null))

위 쿼리를 보면 일단 a, b table이 rjcode 로 조회 되니 일단

select a.rjcode,
          a.rcode,

         max(decode(b.code, '04', code1nm)) aptgu,

         max(decode(b.code, '02', code1nm)) aptname,

         max(decode(b.code, '06', code1nm)) giro,

         max(decode(b.code, '14', code1nm)) bunki,

         max(decode(b.code, '13', code1nm, a.rkita, null,code1nm )) rkita

from

(select
      a.rjcode,
      a.rcode,

      a.raptgu,

      a.rapt,

      a.rgiroflag,

      a.rbun,

      a.rkita

from  dokja a

where    a.rjcode = '120630'
and      a.rcode = '00318'
union

select
      b.rjcode,
      b.rcode,

      '' raptgu,

      '' rapt,

      '' rgiroflag,

      '' rbun,

      '' rkita

from   media b

where    b.rjcode = '120630'
and      b.rcode = '00318'

) a, dokcod b

where ((a.raptgu = b.code1 OR a.rapt = b.code1 OR a.rgiroflag = b.code1 OR

          a.rbun = b.code1 OR a.rkita = b.code1 ) or (a.rkita is null))

group by a.rjcode,  a.rcode

로 해서 대상자를 먼저 만드신 후에 마스터 테이블하고 조인을 거시면 됩니다.

양쪽 OUTER Join과 같은 문제입니다.