조금더 생각을 해봐야되는게

1번이 1980.01.01 부터 2015.12.31일 까지이면

2 / 3 / 4 / 5 번 빠지고 1번만 나와야 되는지...?

-- 제가 문제를 잘 못 이해 햇네요..

WITH TT(NO,FRDT,TODT) AS(
SELECT 1, '1984.09.01',  '1988.07.01' FROM DUAL UNION ALL
SELECT 2, '1988.09.01',  '1990.06.30' FROM DUAL UNION ALL
SELECT 3, '1990.07.01',  '2002.03.31' FROM DUAL UNION ALL
SELECT 4, '2003.03.01',  '2014.03.31' FROM DUAL UNION ALL
SELECT 5, '2005.02.01',  '2014.03.31' FROM DUAL
)
SELECT MIN(NO) NO, TO_CHAR(MIN(DD),'YYYY.MM.DD') FRDT, TO_CHAR(MAX(DD),'YYYY.MM.DD') TODT
FROM (SELECT NO,FRDT
           , CASE WHEN TODT >= TO_CHAR(TO_DATE(LEAD(FRDT) OVER(ORDER BY FRDT),'YYYY.MM.DD')-1,'YYYY.MM.DD')
                  THEN TO_CHAR(TO_DATE(LEAD(FRDT) OVER(ORDER BY FRDT),'YYYY.MM.DD')-1,'YYYY.MM.DD')
                  ELSE TODT
             END AS TODT
      FROM TT) TT
   , (SELECT (SELECT TO_DATE(MIN(FRDT),'YYYY.MM.DD') FROM TT) + ROWNUM -1 AS DD
      FROM DUAL 
      CONNECT BY LEVEL <= (SELECT TO_DATE(MAX(TODT),'YYYY.MM.DD') - TO_DATE(MIN(FRDT),'YYYY.MM.DD') FROM TT) + 1
      )
WHERE DD BETWEEN TO_DATE(FRDT,'YYYY.MM.DD') AND TO_DATE(TODT,'YYYY.MM.DD')
GROUP BY DD-ROWNUM
ORDER BY 1
;

WITH t AS
(
SELECT 1 no, '19840901' frdt, '19880701' todt FROM dual
UNION ALL SELECT 2, '19880901', '19900630' FROM dual
UNION ALL SELECT 3, '19900701', '20020331' FROM dual
UNION ALL SELECT 4, '20030301', '20140331' FROM dual
UNION ALL SELECT 5, '20050201', '20140331' FROM dual
)
SELECT MIN(frdt) frdt
     , MAX(todt) todt
  FROM (SELECT no, frdt, todt
             , SUM(flag) OVER(ORDER BY frdt, todt, no) grp
          FROM (SELECT no, frdt, todt
                     , CASE WHEN MAX(todt) OVER(ORDER BY frdt, todt, no
                                 ROWS BETWEEN UNBOUNDED PRECEDING AND 1 PRECEDING)
                              >= TO_CHAR(TO_DATE(frdt, 'yyyymmdd') - 1, 'yyyymmdd')
                            THEN 0 ELSE 1 END flag
                  FROM t
                )
        )
 GROUP BY grp
 ORDER BY grp
;