统计.txt

完成课程设计

--全年各月份的客房收入
select month(离店时间) as 月份,sum(金额) as 收入
from 历史记录
join 客房编号
on 客房编号=编号
where year(离店时间)=2008
group by month(离店时间)

--一段时间内各客房的入住率
select 客房编号,cast(cast(count(*) as float)/(select count(*) from 历史记录)*100.00 as varchar)+'%' as 入住率
from 历史记录
where '2008-1-1'<=离店时间 and 离店时间<='2008-12-31'
group by 客房编号

--一段时间内各类客房的入住情况
select 名称,cast(cast(count(*) as real)/(select count(*) from 历史记录)*100.00 as varchar)+'%' as 入住率,sum(金额) as 收入金额
from 历史记录
join 客房编号
on 客房编号=编号
join 客房类别
on 客房类别.类别=客房编号.类别
where '2008-1-1'<=离店时间 and 离店时间<='2008-12-31'
group by 名称

改时间就可以啦~~