[sql fiddle demo](http://www.sqlfiddle.com/#!3/811a6/3/0)
此SQL Fiddle解决了您的疑虑。您需要生成一个Calendar表，以便您可以将日期添加到其中。然后，您可以为每个客户计算不同的MonthYears。
create table test( CustomerId int, StartDate date, EndDate date )insert into testvalues (10, '9/1/2013', '9/30/2013'), (10, '9/1/2013', '9/30/2013'), (11, '9/1/2013', '11/30/2013'), (11, '9/1/2013', '11/30/2013'), (11, '9/1/2013', '11/30/2013'), (10, '10/1/2013', '12/31/2013'), (10, '10/1/2013', '12/31/2013'), (11, '12/1/2013', '4/30/2014')create table calendar( MY varchar(10), StartDate date, EndDate date )insert into calendarvalues ('9/2013', '9/1/2013', '9/30/2013'), ('10/2013', '10/1/2013', '10/31/2013'), ('11/2013', '11/1/2013', '11/30/2013'), ('12/2013', '12/1/2013', '12/31/2013'), ('1/2014', '1/1/2014', '1/31/2014'), ('2/2014', '2/1/2014', '2/28/2014'), ('3/2014', '3/1/2014', '3/31/2014'), ('4/2014', '4/1/2014', '4/30/2014')select t.CustomerId, count(distinct c.MY)from test t inner join calendar c on t.StartDate <= c.EndDate and t.EndDate >= c.StartDategroup by t.CustomerId
