一下SQL语句有什么问题？

Question

select @receiveNum=@receiveNum+Count(*)
    from (
     select distinct(ProcessId)
     from dbo.ProcessedInstance
     where ApprovalOrgId=@orgId and AcceptanceTime>@stime and AcceptanceTime<@etime
 )对sql不熟

Answer 1

select @receiveNum=@receiveNum+Count(*)
  from (
select distinct(ProcessId)
from dbo.ProcessedInstance
where ApprovalOrgId=@orgId and AcceptanceTime>@stime and AcceptanceTime<@etime
) t

Answer 2

select @receiveNum=@receiveNum+Count(*)
  from (
select distinct(ProcessId)
from dbo.ProcessedInstance
where ApprovalOrgId=@orgId and AcceptanceTime>@stime and AcceptanceTime<@etime
) t你是吧你面的查询语句作为表来查询，所以得去个别名t