泸州老窖38特曲价格:求助sqlserver高手,急!!!

我现在在做毕业设计关于小区物业管理方面的,我建了一个视图出了错误.
就下面这段sql语句.
create view zongbiaozhichu as select qitazhichu.xuhao, zongbiaofeiyong.nianfen, zongbiaofeiyong.yuefen,
SUM(zongbiaofeiyong.shuifei) AS szzc, SUM(zongbiaofeiyong.dianfei) AS dzzc, SUM(zongbiaofeiyong.meiqifei) AS mqzc, SUM(qitazhichu.feiyong) AS qitazc, SUM(zongbiaofeiyong.shuifei) + SUM(qitazhichu.feiyong)
+ SUM(zongbiaofeiyong.meiqifei) + SUM(zongbiaofeiyong.dianfei) AS heji
FROM zongbiaofeiyong ,qitazhichu where zongbiaofeiyong.nianfen = qitazhichu.nianfen AND zongbiaofeiyong.yuefen = qitazhichu.yuefen
GROUP BY zongbiaofeiyong.nianfen,zongbiaofeiyong.yuefen,qitazhichu.xuhao
其中通过两个表zongbiaofeiyong,qitazhicu的年份和月份连接,将zongbiaofeiyong中的水费,电费,煤气费相加都没错,但是将qitazhichu中的feiyong相加时就跟着zongbiaofeiyong中的水费,电费,煤气费也一起加了两次,数值变成了两倍,因为我的zongbiaofeiyong表中同一年份和月份的有两条记录,而在qitazhichu表中相同的年份和月份的只有一条记录.为什么qitazhichu.feiyong也会加两次呢？我试过了，要是在zongbiaofeiyong中再添加一条相同年份和月份的记录，则qitazhichu.feiyong又再加一次，变为原来的3倍。这是为什么，我的语句中哪里出了错需要修改？
谢谢！