SQL查询以查找日期之间的差异的平均值

我不知道您的RDBMS，但这是来自SQL Server。另外，您的计算之一是错误的-02/09/2011-13/08/2011是20，而不是19。

create table dates (    myDate  date)insert into datesvalues ({d '2011-08-13'}),     ({d '2011-09-02'}),     ({d '2011-09-10'}),     ({d '2011-09-20'});with orderedDates as (    select ROW_NUMBER() OVER (order by myDate) as row, myDate    from dates), datediffs as (    select DATEDIFF(dd, o2.myDate, o1.myDate) as diff    from orderedDates o1 left outer join        orderedDates o2 on o1.row = o2.row + 1)select AVG(cast(diff as decimal))from datediffswhere diff is NOT NULL

产生的结果是12.667：（20 + 8 + 10）/ 3。