These are the kind of questions a first technical round asks, using a small HR table: emp with each employee's id, name, department, hire date, salary, manager id and city. Department heads have no manager.
Interviewers care about correct answers on the awkward cases, so read each question twice. Watch for ties (two people can share a salary), "more than" versus "at least", and missing values. Say out loud, or in a comment, how you handle them; in a real interview that earns as much credit as the code.