Select users belonging only to particular departments

Question

I have the following table with two fields namely a and b as shown below:

create table employe
(
    empID varchar(10),
    department varchar(10)
);
         


        

Answer 1

The following query works when you want employees from departments 'Y' and 'Z' and not 'X'.

select empId from employe 
where empId in (select empId from employe 
                where department = 'Z') 
and empId in (select empId from employe 
              where department = 'Y') 
and empId not in (select empId from employe 
                  where department = 'X') ;

For your second case, simply replace not in with in in the last condition.