CASE Statement in where condition in sql server

we can use case statement in where condition based on our requirement as below :


select * from employee where eid=@eid

 AND 1 =
(
    CASE
        WHEN @periodfrom is not NULL and @periodto is not null
            AND ((PeriodFrom between @periodfrom and @periodto) or(periodTo between @periodfrom and @periodto) )
             THEN 1
        WHEN @periodfrom is  NULL or @periodto is null
             then 1
        WHEN @periodfrom ='' and  @periodto=''
             then 1
        WHEN @periodfrom ='' and  @periodto!=''
         and (periodTo between @periodfrom and @periodto)
             then 1
        WHEN @periodfrom !='' and  @periodto=''
         and (PeriodFrom between @periodfrom and @periodto)
             then 1
    END