Mysql query to get count per months(Mysql查询以获取每月计数)
问题描述
我的用户有一个表,其中有一个名为created"的字段,其中包含注册日期.
I have a table for my users that have a field named "created" that have the registration date.
如何获取包含过去 12 个月内每月注册数量计数的列表?像这样:
How can i get a list that contains a count for the registrations number per month in last 12 months? Like this:
我不习惯使用 mysql,所以直到现在我只知道如何计算去年的注册数量,而不是如何按过去 12 个月对计数进行分组.提前致谢!
I'm not used to working with mysql, so until now i just know how to count the number of registrations in last year, not how to group that count by last 12 months. Thanks in advance!
更新
现在我得到了这个,使用@fthiella 解决方案:
Now I'm getting this, using @fthiella solution:
如何强制查询为我提供 count = 0 的月份?
How can i force query to give me the months with count = 0?
@fthiella 的解决方案(非常感谢!):
Solution by @fthiella (thanks a lot!):
结果:
推荐答案
如果 created 是一个 INT 字段,你应该使用 FROM_UNIXTIME 函数将其转换为日期字段,然后 MONTH 提取月份的函数:
If created is an INT field, you should use FROM_UNIXTIME function to convert it to a date field, and then MONTH function to extract the month:
这将计算过去 12 个月内创建的所有行.请注意,最好也按年份分组:
this will count all the rows that have been created in the last 12 months. Please notice that it's probably better to also group by the YEAR:
如果您需要计算注册号而不是行数,您可以使用类似
If you need to count the registration numbers instead of the rows, you could use something like
跳过空值,或
只计算不同的.
编辑
如果您还需要显示 count=0 的月份,我会使用这样的查询来返回当前和上一年的所有月份:
If you also need to show months that have count=0, I would use a query like this that returns all of the months for the current and for the previous year:
然后我会使用一个LEFT JOIN,它返回第一个查询的所有行,并且只返回匹配的第二个查询的行:
And then I'd use a LEFT JOIN, that returns all of the rows of the first query, and only the rows of the second query that matches:
(请注意,这里我只考虑过去 12 个月,所以如果我们在 2013 年 4 月中旬,它将计算 2012 年 5 月 - 4 月 13 日之间的行数,如果这不是正确的行为,请告诉我)
(please notice that here I am considering just the last 12 months, so if we are in the middle April 2013 it will count rows in the interval May 2012 - April 13, if this is not the correct behaviour please let me know)
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