帮助优化SQL查询

Question

我有跟踪表tbl_track与id,session_id,created_date字段

我需要计算一天的唯一session_id

在这里我得到了:

select count(0) 
from (
       select distinct session_id
       from tbl_track 
       where created_date between getdate()-1 and getdate()
       group by session_id
)tbl

我觉得它可能是更好的解决方案

Answer 1

select count(distinct session_id)
from tbl_track
where created_date between getdate()-1 and getdate()

Answer 2

为什么不完全按照你的要求去做？

   select count(distinct session_id)
   from tbl_track  
   where created_date between getdate()-1 and getdate()