请教多表查询按日期汇总显示？

SQL code

select CheckInTime,sum(case when b.mingcheng='北京' then a.renshu else 0 end) '北京',sum(case when b.mingcheng='上海' then a.renshu else 0 end) '上海',sum(case when b.mingcheng='杭州' then a.renshu else 0 end) '杭州' from Tbl_checkIn a,tbl_PiaoLei b where a.piaolei=b.bianhao  and CheckInTime>= '2012-10-01'  and CheckInTime<= '2012-10-07'  and CheckInNo='01'  GROUP BY CheckInTime

请教各位老师，这个是查询几天各地区的合计人数，如何把查询出来的结果汇总显示每天多少人呢？谢谢！
现在查询结果是这样




希望查询结果是这样


[解决办法]
select convert(varchar(8),checkintime),sum(case when ....背京 end),sum(....
from tb group by convert(varchar(8),checkintime)