Recently, the company wants to count the number of registered users, sales volume, and transaction volume every week within a year. Share the problems encountered in the development. Please forgive me if there are any mistakes in the article
1 MySQL week number statistics (week function )
First, let's talk about MySQL database statistics using week(Str/date,number) The first parameter is a string or date, and the second parameter is a number
Next, I will introduce an example of the use of the week function
select week('2015-11-17',1) November 17 , 2015 is the 47th week in the new year
The value of the second parameter number in the week function is used
| Number |
first day of the week |
Scope |
Week 1 is the first week |
| 0 |
Sunday |
0～53 |
There is a Sunday in the year |
| 1 |
on Monday |
0～53 |
There are more than 3 days in the current year |
| 2 |
Sunday |
1～53 |
There is a Sunday in the year |
| 3 |
on Monday |
1～53 |
There are more than 3 days in the current year |
| 4 |
Sunday |
0～53 |
There are more than 3 days in the current year |
| 5 |
on Monday |
0～53 |
There is a Monday in the year |
| 6 |
Sunday |
1～53 |
There are more than 3 days in the current year |
| 7 |
on Monday |
1～53 |
There is a Monday in the year |
WEEK('2015-11-17') uses only one parameter, and its second parameter is the default value of default_week_format , which defaults to 0 in MySQL
The following is the sql used to count the number of registered users per week during the development process
where post_date is the field of the registration time
SELECT WEEK(u.post_date,1),COUNT(*)
FROM USERS u WHERE 1=1
AND u.post_date>='2015-01-01'
AND u.post_date<='2015-12-31'
GROUP BY WEEK(u.post_date,1)
Note: The week parameter uses 1 to match our normal week number display
Mysql also has a function of WEEKOFYEAR(d)
Week of the year. The range is from 1 to 53 , equivalent to WEEK(d,3) .
But for some special cases, he will have some problems, such as querying December 31 , 2014 , using weekofyear , he will regard that day as the first week of 2015
