mysql数据库按周统计
需求:统计本周的数据,上一周的数据,不管是不是跨年,星期一是第1天。
week函数总共分为8种情况:
- 以星期一还是星期天做为一周的第1天(一周7天从星期一到星期天)
- 一年的第1个星期,4天以上在本年还是星期的第1天在本年。
- 一年开始属于去年的天,返回0还是上一年的星期数。
This function returns the week number for date. The two-argument form of WEEK()
enables you to specify whether the week starts on Sunday or Monday and whether the return value should be in the range from 0
to 53
or from 1
to 53
. If the mode argument is omitted, the value of the default_week_format
system variable is used. See Section 5.1.8, “Server System Variables”.
The following table describes how the mode argument works.
Mode | First day of week | Range | Week 1 is the first week … |
---|---|---|---|
0 | Sunday | 0-53 | with a Sunday in this year |
1 | Monday | 0-53 | with 4 or more days this year |
2 | Sunday | 1-53 | with a Sunday in this year |
3 | Monday | 1-53 | with 4 or more days this year |
4 | Sunday | 0-53 | with 4 or more days this year |
5 | Monday | 0-53 | with a Monday in this year |
6 | Sunday | 1-53 | with 4 or more days this year |
7 | Monday | 1-53 | with a Monday in this year |
For mode values with a meaning of “with 4 or more days this year,” weeks are numbered according to ISO 8601:1988:
- If the week containing January 1 has 4 or more days in the new year, it is week 1.
- Otherwise, it is the last week of the previous year, and the next week is week 1.
mysql> SELECT WEEK('2008-02-20');
-> 7
mysql> SELECT WEEK('2008-02-20',0);
-> 7
mysql> SELECT WEEK('2008-02-20',1);
-> 8
mysql> SELECT WEEK('2008-12-31',1);
-> 53
If a date falls in the last week of the previous year, MySQL returns 0
if you do not use 2
, 3
, 6
, or 7
as the optional mode argument:
mysql> SELECT YEAR('2000-01-01'), WEEK('2000-01-01',0);
-> 2000, 0
One might argue that WEEK()
should return 52
because the given date actually occurs in the 52nd week of 1999. WEEK()
returns 0
instead so that the return value is “the week number in the given year.” This makes use of the WEEK()
function reliable when combined with other functions that extract a date part from a date.
If you prefer a result evaluated with respect to the year that contains the first day of the week for the given date, use 0
, 2
, 5
, or 7
as the optional mode argument.
mysql> SELECT WEEK('2000-01-01',2);
-> 52
Alternatively, use the YEARWEEK()
function:
mysql> SELECT YEARWEEK('2000-01-01');
-> 199952
mysql> SELECT MID(YEARWEEK('2000-01-01'),5,2);
-> '52'
原文地址:https://www.cnblogs.com/mozq/p/12389478.html