select * from user a
where datediff(day,注册时间,getdate())>15
and not exists(select 1 from 销售表 where 用户ID=a.用户ID and datediff(day,销售日期,getdate())<=15)
where datediff(day,注册时间,getdate())>15
and not exists(select 1 from 销售表 where 用户ID=a.用户ID and datediff(day,销售日期,getdate())<=15)
from user表 --和当前时间比较select *
from 销售表,user表
where user表.id=销售表.id
and diffdate(day,注册时间,getdate())<15 -- 和当前时间比较