select d.name, e.id from Employee e
join Departament d on d.id = e.dep_id
where e.id = (
    select s.eid from (
        select ee.id as eid, @rowid:=@rowid+1 as rowid from Employee ee, (SELECT @rowid:=0) as init
        where ee.dep_id = d.id
        order by ee.salary desc
     ) s
    where s.rowid = 5
)