如果IN子查询没有行,如何返回所有行？

Question

以下是示例查询

Select *
  from tb.Users u
 where u.Approved = 1
   and u.userID IN ( SELECT us.UserID us
                       FROM tb.UserStatementes us
                      WHERE us.LogDate between date1 and date2 )

我需要选择IN子句中的所有用户,但是如果子查询没有返回记录,我需要选择所有用户(即忽略IN子句)

Answer 1

Select *
  from tb.Users u
 where u.Approved = 1
   and (
    u.userID IN ( SELECT us.UserID us
                        FROM tb.UserStatementes us
                       WHERE us.LogDate between date1 and date2 
                       )
    or not exists (
        select 1
          from tb.UserStatementes us
          where us.LogDate between date1 and date2
        )
      )