从周号获取一周的第一天 [英] Get First Day Of Week From Week Number

问题描述

在Oracle中，有没有简单的方法可以根据周数获得一周的第一天?

In Oracle, is there a straightforward way to get the first day of the week given a week number?

例如，今天的日期是2012年12月4日.如果我运行: 从双中选择to_char(sysdate，'WW'); 返回第49周.

For example, today's date is 12/4/2012. If I run: select to_char(sysdate,'WW') from dual; It returns 49 for the week number.

我想做的是第一天返回2012年12月2日...给定第49周(假设星期日为一周的第一天).

What I would like to do is somehow return 12/2/2012 for the first day...given week 49 (assuming Sunday as first day of the week).

有什么想法吗?预先感谢您的帮助！

Any ideas? Thanks in advance for any help!

推荐答案

尝试一下:

select next_day(max(d), 'sun') requested_sun
  from (select to_date('01-01-2012', 'dd-mm-yyyy') + (rownum-1) d from dual connect by level <= 366)
 where to_char(d, 'ww') = 49-1;

只需设置您的年份to_date('01-01-2012'和第1周49-1(如果适用).

just set your year to_date('01-01-2012' and week number-1 49-1 as applicable.

2008年第49周的星期天?

the sunday in the 49th week of 2008?

SQL> select next_day(max(d), 'sun') requested_sun
  2    from (select to_date('01-01-2008', 'dd-mm-yyyy') + (rownum-1) d from dual connect by level <= 366)
  3   where to_char(d, 'ww') = 49-1;

REQUESTED
---------
07-DEC-08

和2012

SQL> select next_day(max(d), 'sun') requested_sun
  2    from (select to_date('01-01-2012', 'dd-mm-yyyy') + (rownum-1) d from dual connect by level <= 366)
  3   where to_char(d, 'ww') = 49-1;

REQUESTED
---------
02-DEC-12

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