MySQL查询以检索给定时间段内的最大项目数

Question

I've a table like attached.

I want to find the "number of items in a certain month which has maximum entries in the database".

For instance, Jan has 10 entries, Feb has 13 entries, Mar has 8 entries.

I want to find the the number 13 for Feb from the database as it has the max entries. How do I check the time range in the query?

Answer 1

You can group all of your realeasedates by month and year to get a count like this:

SELECT MONTH(releasedate) AS month, YEAR(releasedate) as year, count(r_id) AS number
FROM my_table 
GROUP BY YEAR(releasedate), MONTH(releasedate)
ORDER BY YEAR(releasedate), MONTH(releasedate)

This'll give you something like this:

+--------+--------+--------+
| month  |  year  | number |
+--------+--------+--------+
|   1    |  2013  |   13   |
|   2    |  2013  |    8   |

Then you could select the maximum like this:

SELECT MONTH(releasedate) AS month, YEAR(releasedate) as year, count(r_id) AS number
FROM my_table 
GROUP BY YEAR(releasedate), MONTH(releasedate)
ORDER BY count(r_id)
LIMIT 1

Which'll give you:

+--------+--------+--------+
| month  |  year  | number |
+--------+--------+--------+
|   4    |  2013  |   19   |
+--------+--------+--------+

Which'll represent the highest month

Answer 2

SELECT COUNT(*) FROM `mytable` WHERE releasedate >= DATE '2013-02-01' AND releasedate <= DATE '2013-02-28'

That should work

EDIT:

As suggested by lafor...

WHERE YEAR(releasedate)=2013 AND MONTH(releasedate)=2

should also work