比较复杂的语句，请大家看看，有关同比，环比的.

[生活的信仰]

 create table #car
(years int,  --年份
 months int, --月份
 num int,    --销售数量
 area nvarchar(28) --地域          
 )
insert into #car
select 2008,1,30,'华中' union all select 2008,2,20,'华南' union all select 2008,12,40,'华北' union all
select 2009,1,15,'华中' union all select 2009,2,50,'华南' union all select 2009,12,70,'华北' union all
select 2010,1,130,'华中' union all select 2010,2,40,'华南' union all select 2010,12,100,'华北' 

 --写出  years months area num  同比, 环比,累计销量,累计同比,累计环比

 --解释： 同比     = (当年当月销量 -去年当月销量)/去年当月销量 
 --      环比     = (当年当月销量 -上月销量) / 上月销量
 --      累计销量 = 当年累计销量之和  
select area,years,months,num from #car 

[silentcross]

同比，环比类似

Select
(thisyear.num - lastyear.num) / lastyear.num
From
#car lastyear
inner join
#car thisyear
on
lastyear.years = thisyear.years -1 and
lastyear.month = thisyear.month and
lastyear.area = thisyear.area

[--小F--]

select
isnull(a.num,0)-isnull(b.num,0)/isnull(b.num,0) as 同比,
...
力气活...

[-晴天]

好像前不久写过一个类似的...