最近，同事需要从数个表中查询用户的业务和报告数据，写了一个SQL语句，查询比较慢：

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 ) an..