날짜 관련 쿼리 입니다. 한달을 요일별로 구함..

SELECT SUM(DECODE(A.A2, '1', A.A3, null)) 일요일,
       SUM(DECODE(A.A2, '2', A.A3, null)) 월요일,
       SUM(DECODE(A.A2, '3', A.A3, null)) 화요일,
       SUM(DECODE(A.A2, '4', A.A3, null)) 수요일,
       SUM(DECODE(A.A2, '5', A.A3, null)) 목요일,
       SUM(DECODE(A.A2, '6', A.A3, null)) 금요일,
       SUM(DECODE(A.A2, '7', A.A3, null)) 토요일
FROM
   ( SELECT rownum + 7 - to_number(TO_CHAR(TO_DATE('200312' || TO_CHAR(rownum),'YYYYMMDD'),'D')) as A1,
            TO_CHAR(TO_DATE('200312' || TO_CHAR(rownum), 'YYYYMMDD'), 'D') as A2,
            rownum as A3
     FROM user_objects
     WHERE rownum <= 31
       AND rownum > 0
       And TO_CHAR(LAST_DAY(TO_DATE('200312' || '01', 'YYYYMMDD')), 'DD')>= LTRIM(TO_CHAR(rownum, '00'))
   ) A
GROUP BY A.A1

일요일     월요일     화요일     수요일     목요일     금요일     토요일
------ ---------- ---------- ---------- ---------- ---------- ----------
                   1           2              3           4          5          6
     7             8           9            10          11         12         13
    14           15         16             17          18         19         20
    21           22         23             24          25         26         27
    28           29         30             31
 

www.en-core.com 에 이추형님의  글 입니다.