Statistical data sql writing by year, month and day
I have recently encountered the problem of statistical calculations for the year, month, and day, and I haven't got a clue for a short time (a few seconds), so I summarize it and record it.
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1.先看数据库，我随便找了一个有时间的数据库，没仔细去琢磨，将就用。
2. Let's first recognize a few functions
uploadtime: 2019-12-08 14:49:30
year (uploadtime) Get the year in the time field, the result is 2019
month (uploadtime) Get the month in the time field, the result is 12
day (uploadtime) Get the day in the time field , The result is 08
3. Statistics by year:
select year(uploadtime) as yy,count(*),sum(filetypeid) from sys_base_fileindex GROUP BY yy
4. Statistics by month:
select year(uploadtime) as yy, month(uploadtime) as mm,count(*),sum(filetypeid) from sys_base_fileindex GROUP BY yy,mm
5. By daily statistics
select year(uploadtime) as yy, month(uploadtime) as mm,day(uploadtime) as dd ,count(*),sum(filetypeid) from sys_base_fileindex GROUP BY yy,mm,dd
Summary:
Here is a guideline, the order of multiple fields of group by:
GROUP BY X means to put all records with the same X field value into a group.
GROUP BY X, Y means put all records with the same X field value and Y field value into a group
GROUP BY X, Y, Z means put all records with the same X field value and Y field value and Z field value Put records in a group
