各位给看看怎么将表中重复行数据统计出来

各位给看看如何将表中重复行数据统计出来
值日表   zrb

值日人 people，房间 号  roomnum

表数据如下 

people         roomnum

   A                    1
   A                    1
   B                    3
   A                    4
   B                    3
   B                    2
   C                    1
   C                    2

要求实现如下统计
   
   people          roomnum                 count
        A                       1                             2
        A                       4                             1
        B                       2                             1
        B                       3                             2
        C                       1                             1
        C                       2                             1 

值日人，房间号都是不定的，大家给看看啊
------解决思路----------------------

select people,roomnum,COUNT(1) AS    count
from ZRB
GROUP BY people,roomnum