如何计算下周的数量？(How Do I Calculate the Number of the Following Week?)

 我需要计算一周后的一周数。 这对于一年中的大多数星期来说是微不足道的，但不是在年末/年初。 例如，如果我需要知道2013年第52周之后的一周。 
 
 我想使用defaul_week_format 3，即a）从星期一（而不是星期日）开始的星期b）一年内的编号从1开始（而不是0）和c）第1周是第一周以上今年3天。 
 
 我计算2014年第36周后一周的方法如下： 
 
SELECT WEEK(DATE_ADD(STR_TO_DATE('W36 2014 Tuesday', 'W%V %X %W'), INTERVAL 1 WEEK))
 
 对于此示例，我计算第36周的星期二日期，添加一周，并计算当天的星期。 这可行，但即使没有增加一周，我也有这种奇怪的行为： 
 
 它适用于default_week_format 0： 
 
SET @@local.default_week_format=0;
SELECT STR_TO_DATE('W36 2014 Tuesday', 'W%V %X %W');
-> Tuesday of week 36 is 2014-09-09
SELECT week('2014-09-09');
-> 2014-09-09 is in week 36
 
 到目前为止，非常好：36周的第二周是第36周。 
 
 但是这个简单的实验不适用于default_week_format 3： 
 
SET @@local.default_week_format=3;
SELECT STR_TO_DATE('W36 2014 Tuesday', 'W%V %X %W');
-> Tuesday of week 36 is 2014-09-09
-> This is wrong, because numbering should start with 1 (instead of 0 now)!
-> Tuesday of week 36 should be 2014-09-02
SELECT week('2014-09-09');
-> 2014-09-09 is in week 37
 
 所以MySQL告诉我36周的星期二是在第37周！ 
 
 我唯一的解释是： 
 
 
 
 week（）将default_week_format考虑在内 
 
 
 str_to_date（）忽略default_week_format 
 
 
 如何强制MySQL函数str_to_date使用default_week_format？ 
 
 或者：我怎么能计算下一周的数量？ 我也可以在PHP中完成它，但我从MySQL数据库中获取周数。 
 
 谢谢你的帮助！ 

I need to calculate the number of the week following a given week. This is trivial for most weeks within the year, but not at the end / beginning of the year. For example if I need to know the week following week 52 of 2013.
 
I would like to use the defaul_week_format 3, i.e. a) the weeks start with Monday (instead of Sunday) b) the numbering within a year starts with 1 (instead of 0) and c) week number 1 is the first week with more than 3 days this year.
 
My approach to e.g. calculate the week after week 36 2014 is the following:
 
SELECT WEEK(DATE_ADD(STR_TO_DATE('W36 2014 Tuesday', 'W%V %X %W'), INTERVAL 1 WEEK))
 
For this example I calculate the date of Tuesday in week 36, add one week, and calculate the week of this day. This would work, but even without adding one week, I have this strange behaviour:
 
It works for the default_week_format 0:
 
SET @@local.default_week_format=0;
SELECT STR_TO_DATE('W36 2014 Tuesday', 'W%V %X %W');
-> Tuesday of week 36 is 2014-09-09
SELECT week('2014-09-09');
-> 2014-09-09 is in week 36
 
So far, so good: Tuesday of week 36 is in week 36.
 
But this simple experiment does NOT work for default_week_format 3:
 
SET @@local.default_week_format=3;
SELECT STR_TO_DATE('W36 2014 Tuesday', 'W%V %X %W');
-> Tuesday of week 36 is 2014-09-09
-> This is wrong, because numbering should start with 1 (instead of 0 now)!
-> Tuesday of week 36 should be 2014-09-02
SELECT week('2014-09-09');
-> 2014-09-09 is in week 37
 
So MySQL tells me that Tuesday of week 36 is in week 37!
 
My only explanation for this:
 
 
 
week() takes default_week_format into account
 
 
str_to_date() ignores the default_week_format
 
 
How can I force MySQL function str_to_date to use the default_week_format?
 
Or: How else can I calculate the number of the following week? I could also do it in PHP, but I get the weeks' numbers from a MySQL database.
 
Thanks for any help!

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