求两个日期范围内有多少个星期天？

 

方法一：
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select count(*)
  from (select trunc(TO_DATE('2005/11/04', 'YYYY/MM/DD'), 'MM') + rownum - 1 as d
          from dba_objects) x
 where trunc(x.d) between trunc(TO_DATE('2005/11/04', 'YYYY/MM/DD')) and
       trunc(TO_DATE('2007/04/13', 'YYYY/MM/DD'))
   and to_char(x.d, 'd') = '1';

蓝色的为开始日期，红色的为结束日期。

注意：to_char(x, 'd'),星期天是'1'，星期一是'2'.....星期六是'7'
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方法二：
select trunc((to_date('2006/11/23','YYYY/MM/DD')-NEXT_DAY(to_date('2006/10/20','YYYY/MM/DD'),1))/7)+1 from dual;