테이블 설명

PUB0900 코드 마스터

PUB0910  코드 디테일

기타 : 업무용 테이블

다음 쿼리에서 코드값을 가져오는 부분을 이해할 수 없습니다.(빨간색)

SELECT A.* FROM (
SELECT A.*, LEAD(STATUS, 1, 0) OVER(ORDER BY PR_NO, PO_REV DESC) AS BEFORE_STATUS FROM (
 SELECT
             A.PURREQ_NO,
             A.PURREQ_TITLE,
             A.PURREQ_ID,
             (SELECT MAX(USER_NAME_K) FROM PUB0130V WHERE ACCT_ID = A.PUR_CHARGE) AS PUR_CHARGE,
             (SELECT MAX(USER_NAME_K) FROM PUB0130V WHERE ACCT_ID = A.SUPT_CHARGE) AS SUPT_CHARGE,
             (SELECT MAX(USER_NAME_K) FROM PUB0130V WHERE ACCT_ID = A.SPOT_CHARGE) AS SPOT_CHARGE,
             A.REQ_DATE,
             SUBSTR(A.DEL_START,0,4) || '-' || SUBSTR(A.DEL_START,5,2) || '-' || SUBSTR(A.DEL_START,7,2) || ' ~ '|| SUBSTR(A.DEL_END,0,4) || '-'
 || SUBSTR
  (A.DEL_END,5,2) || '-' || SUBSTR(A.DEL_END,7,2)  DEL_DATE ,
             A.STATUS,
             A.PURREQ_ID AS  PURREQ_ID2,
             ( SELECT CODE_NAME_KOR
                  FROM PUB0910T
                  WHERE COMM_CODE_ID = (SELECT COMM_CODE_ID
                                                FROM PUB0900T
                                                WHERE COMM_CODE = 'PUR_PR_STATUS'
                                                AND CODE = A.STATUS) ) AS STATUS2,
             (SELECT COUNT(*) CNT FROM PUR1060T WHERE PURREQ_ID= A.PURREQ_ID  )  ITEM_COUNT
             , A.PR_NO, A.DEPT_CD, A.PO_REV
 FROM PUR1050T A
      ,(
  SELECT RFQ_ID, RFQ_STAT, DEPT_CD, PR_NO
  FROM PUR3000T
  WHERE RFQ_ID IN (
             SELECT
                  MAX(RFQ_ID) RFQ_ID
             FROM PUR3000T
             WHERE (DEPT_CD, PR_NO) IN (
                   SELECT
                         DEPT_CD, PR_NO
                   FROM PUR1050T
                   WHERE 1=1
                     AND PR_NO IS NOT NULL
                   GROUP BY DEPT_CD, PR_NO
                   HAVING COUNT(*) > 1
                   )
             GROUP BY DEPT_CD, PR_NO
          )
      ) B
 WHERE A.DEPT_CD = B.DEPT_CD
   AND A.PR_NO = B.PR_NO
   AND NOT EXISTS (
             SELECT '1'
             FROM PUR5000T C
             WHERE C.RFQ_ID = B.RFQ_ID
      )
 ) A
 ) A
 WHERE 1=1
   AND A.PO_REV > 0
   ORDER BY PURREQ_NO DESC
;

근데 PUB0900에는 CODE란 필드가 없습니다. 에러가 나야 되는 건 아닌가요?

이렇게 되어야 하는데

             ( SELECT CODE_NAME_KOR
                  FROM PUB0910T
                  WHERE COMM_CODE_ID = (SELECT COMM_CODE_ID
                                                FROM PUB0900T
                                                WHERE COMM_CODE = 'PUR_PR_STATUS'

                                               ) AND CODE = A.STATUS) AS STATUS2,

결과는 똑같습니다.

왜 그런지 이유를 설명해 주실 분?

참고로 오라클 9i 입니다.