在sqlserver中如何使用CTE解决复杂查询问题

Select 
S.Name,
S.AccountantCode,
(
Select COUNT(*) from (
Select Distinct BusinessBackupId from Biz_BusinessBackupCustomer where Id in (
Select BusinessBackupCustomerId from Rpt_RegistForm where ( SignatureCPA1Id=S.Id or SignatureCPA2Id=S.Id ) and DocStatus=30 
) ) T 
) as 'BNum',
(case when R.Id is null then 0 else 1 end ) as 'Num', 
R.ReportBackupDate 
from 
Base_Staff S 
left join Rpt_RegistForm R on ( R.SignatureCPA1Id=S.Id or R.SignatureCPA2Id=S.Id ) and R.DocStatus=30 
where S.UserType=3 

With CTE as
(
select 
    --s.Id as S_ID,
    s.Name ,s.AccountantCode,
    r.BusinessBackupCustomerId --, r.Id as R_ID ,r.SignatureCPA1Id,r.SignatureCPA2Id
from  Base_Staff S 
left join Rpt_RegistForm  R 
    on ( R.SignatureCPA1Id=S.Id or R.SignatureCPA2Id=S.Id ) and r.DocStatus=30 
where s.UserType=3 
)
select t0.*
,(
 Select COUNT(*) from (
  Select Distinct BusinessBackupId 
  from Biz_BusinessBackupCustomer b
  inner join CTE on b.Id =CTE.BusinessBackupCustomerId
  where t0.AccountantCode=CTE.AccountantCode
) t1
) as '约定书数'
from 
(
select Name, AccountantCode,COUNT( BusinessBackupCustomerId) as '报告数'
from CTE
group by Name,AccountantCode
) t0