[Oracle] Column 값 변화 시점 구하기- SQL

요구사항.

값의 변화시점 확인하는 쿼리.

질문 내용

WITH t AS (
SELECT '20180718131317' dd, 'a' cc from dual union all
SELECT '20180718131318', 'a' from dual union all
SELECT '20180718131319', 'b' from dual union all <==
SELECT '20180718131320', 'b' from dual union all
SELECT '20180718131321', 'b' from dual union all
SELECT '20180718131322', 'b' from dual union all
SELECT '20180718131323', 'b' from dual union all
SELECT '20180718131324', 'b' from dual union all
SELECT '20180718131325', 'b' from dual union all <==
SELECT '20180718131326', 'a' from dual union all
SELECT '20180718131327', 'a' from dual union all
SELECT '20180718131328', 'a' from dual union all
SELECT '20180718131329', 'a' from dual union all
SELECT '20180718131330', 'a' from dual union all
SELECT '20180718131331', 'a' from dual union all
SELECT '20180718131332', 'a' from dual union all
SELECT '20180718131333', 'a' from dual union all
SELECT '20180718131334', 'a' from dual union all
SELECT '20180718131335', 'a' from dual union all
SELECT '20180718131336', 'b' from dual union all <==
SELECT '20180718131337', 'b' from dual union all
SELECT '20180718131338', 'b' from dual union all
SELECT '20180718131339', 'b' from dual union all
SELECT '20180718131340', 'b' from dual union all
SELECT '20180718131341', 'b' from dual union all <==
SELECT '20180718131342', 'a' from dual union all
SELECT '20180718131343', 'a' from dual union all
SELECT '20180718131344', 'a' from dual
)

구하고 싶은 데이터는
'b'가 시작하는 시각 : '20180718131319'
'b'가 끝나는 시각 : '20180718131325'
다시 'b'가 시작되는 시각 : '20180718131336'
'b'가 끝나는 시각 : '20180718131341'
입니다.

쿼리는 어떻게 생성해야 하는지요?

응답코드

WITH t AS
(
SELECT '20180718131317' dd, 'a' cc FROM dual
UNION ALL SELECT '20180718131318', 'a' FROM dual
UNION ALL SELECT '20180718131319', 'b' FROM dual  -- s
UNION ALL SELECT '20180718131320', 'b' FROM dual
UNION ALL SELECT '20180718131321', 'b' FROM dual
UNION ALL SELECT '20180718131322', 'b' FROM dual
UNION ALL SELECT '20180718131323', 'b' FROM dual
UNION ALL SELECT '20180718131324', 'b' FROM dual
UNION ALL SELECT '20180718131325', 'b' FROM dual  -- e
UNION ALL SELECT '20180718131326', 'a' FROM dual
UNION ALL SELECT '20180718131327', 'a' FROM dual
UNION ALL SELECT '20180718131328', 'a' FROM dual
UNION ALL SELECT '20180718131329', 'a' FROM dual
UNION ALL SELECT '20180718131330', 'a' FROM dual
UNION ALL SELECT '20180718131331', 'a' FROM dual
UNION ALL SELECT '20180718131332', 'a' FROM dual
UNION ALL SELECT '20180718131333', 'a' FROM dual
UNION ALL SELECT '20180718131334', 'a' FROM dual
UNION ALL SELECT '20180718131335', 'a' FROM dual
UNION ALL SELECT '20180718131336', 'b' FROM dual  -- s
UNION ALL SELECT '20180718131337', 'b' FROM dual
UNION ALL SELECT '20180718131338', 'b' FROM dual
UNION ALL SELECT '20180718131339', 'b' FROM dual
UNION ALL SELECT '20180718131340', 'b' FROM dual
UNION ALL SELECT '20180718131341', 'b' FROM dual  -- e
UNION ALL SELECT '20180718131342', 'a' FROM dual
UNION ALL SELECT '20180718131343', 'a' FROM dual
UNION ALL SELECT '20180718131344', 'a' FROM dual
)
SELECT cc
     , MIN(dd) sdd
     , MAX(dd) edd
  FROM (SELECT dd, cc
             , ROW_NUMBER() OVER(ORDER BY dd)
             - ROW_NUMBER() OVER(PARTITION BY cc ORDER BY dd) gb
          FROM t
        )
-- WHERE cc = 'b'
 GROUP BY cc, gb
 ORDER BY sdd
;

활용

참조

• [구루비 - Database Q&A(http://www.gurubee.net/article/80762)]
•