用SQL实现年日历的方法

在很多论坛上见过要求使用SQL实现年日历例子，今天就自己动手写了，代码实现如下：

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 ----日历实现

 with test as
  (select level as id_seq, trunc(sysdate, \'y\') + level - 1 as rq
     from dual
   connect by level <----得出一年的起止日期

              add_months(trunc(sysdate, \'y\'), 12) - trunc(sysdate, \'y\') + 1),
 test1 as---穷举出一年的所有日期

  (select id_seq, rq, to_char(rq, \'iw\') as iw, to_char(rq, \'mm\') as ---iw为一年当中的第几周

     from test)
 select max(case to_char(rq, \'dy\')
              when \'星期一\' then
               to_char(rq, \'dd\')
            end) as mon,
        max(case to_char(rq, \'dy\')
              when \'星期二\' then
               to_char(rq, \'dd\')
            end) as tus,
        max(case to_char(rq, \'dy\')
              when \'星期三\' then
               to_char(rq, \'dd\')
            end) as wen,
        max(case to_char(rq, \'dy\')
              when \'星期四\' then
               to_char(rq, \'dd\')
            end) as thur,
        max(case to_char(rq, \'dy\')
              when \'星期五\' then
               to_char(rq, \'dd\')
            end) as fri,
        max(case to_char(rq, \'dy\')
              when \'星期六\' then
               to_char(rq, \'dd\')
            end) as sta,
        max(case to_char(rq, \'dy\')
              when \'星期日\' then
               to_char(rq, \'dd\')
            end) as sun
   from test1
  group by im, iw
  order by im, iw

实现的关键点：
1、获取到一年的起止日期
2、使用穷举法列出一年的所有日期
3、熟悉将日期转化成星期、第几周和获取月份的函数
4、根据月份、第几周分组排序即可

来自 “ ITPUB博客 ” ，链接：http://blog.itpub.net/29507357/viewspace-1208835/，如需转载，请注明出处，否则将追究法律责任。

转载于:http://blog.itpub.net/29507357/viewspace-1208835/