select * from tablename

where time>= case when DATEDIFF(DAY,DATEADD(week,DATEDIFF(week,0,getdate()),0),GETDATE())=0

                       then DATEADD(week,-1,DATEADD(week,DATEDIFF(week,0,GETDATE()),0))

　　　　　　else DATEADD(week,DATEDIFF(week,0,getdate()),0)

　　　　　　end

 

逻辑 ：如果当前是周一，就查询上周一以来的数据，否则就查询本周数据；

//上周一

select  DATEADD(week,-1,DATEADD(week,DATEDIFF(week,0,GETDATE()),0)) 

//本周一

select  DATEADD(week,DATEDIFF(week,0,getdate()),0)