记一次sql server 性能调优，查询从20秒至2秒

select*
from(
select *,ROW_NUMBER()
OVER (ORDER BY sc desc) as rank  
from(
select *,
case when ( 40-(a.p*(
case when a.p > 0 then 1 
else -0.5 end)))<=30then 30 
else ( 40-(a.p*(
case when a.p > 0 then 1 
else -0.5 end)))end as sc   
from (
select * from (
select a.ProjectNumber, a.ProjectName, 
a.BaojianNumber, a.BaojianName, a.ToubiaoPerson,
sum(UnitPrice) as sumPrice, 
b.price as avgPrice, 
((sum(UnitPrice)-b.price)/nullif(b.price,0)*100) as p,
sum(case when UnitPrice>b.price then b.price 
else UnitPrice end )as pprice,
sum(case when UnitPrice>MaxPrice then 1 
else 0 end ) as countChao
from ToubiaoDetailTest1 a
join (
select ProjectNumber, ProjectName, 
BaojianNumber, BaojianName, avg(price) as price
from(
select * from(
select ProjectNumber, ProjectName, 
BaojianNumber, BaojianName, ToubiaoPerson, 
SUM(UnitPrice) as price,
SUM(case when UnitPrice>MaxPrice then 1 
else 0 end ) as countChao
from ToubiaoDetailTest1  
group BY ProjectNumber, ProjectName, BaojianNumber, 
BaojianName, ToubiaoPerson
) tt where tt.countChao = 0
) t group by ProjectNumber, ProjectName, 
BaojianNumber, BaojianName
) b on a.ProjectNumber=b.ProjectNumber and 
a.ProjectName=b.ProjectName and 
a.BaojianNumber=b.BaojianNumber and 
a.BaojianName=b.BaojianName
group by a.BaojianNumber, a.BaojianName, 
a.ProjectNumber, a.ProjectName, a.ToubiaoPerson, b.price    
) tt where tt.countChao=0
) a  
) b
) t   
order by rank 
}