查找在DB2中创建的每月平均记录数

Question

以下是查找创建的每月平均记录数的查询。 创建日期为TIMESTAMP

select year,month, (ymcount/maxmonthdays) as monthaverage ymcount  from (
select year,month,maxmonthdays, count(1) ymcount  from (
SELECT year(created) as year, MONTHNAME(created) as month,
day(date(date(created))-(day(date(created)) -1) days + 1 month -1 day)  as maxmonthdays 
FROM tablename )
group by year,month,maxmonthdays );

注意：要查找一个月内的最大天数，我使用了以下命令。

day(date(date(created))-(day(date(created)) -1) days + 1 month -1 day)  as maxmonthdays 

可以使用DB2版本9.7之后支持的last_day函数，我使用的是版本9.5。