m) Find all employees who have no job according to the database (i.e. those who are registered in the employee table but not in the works table).  Hint: use the except construction.

n) Find all employees who have no manager functions according to the database.

o) Find the average salary of employees of the First Bank Corporation.

p) Give a list of companies with the number of employees for each company mentioned in the company table.
    Hint:  er kunnen ook companies met nul medewerkers in het antwoord voorkomen.