(g) Which students have NOT enroled in anything?
    If your result is not correct, make sure you understand why
    your query did not give you the result you expected, and find
    out how to formulate the correct query.

(h) List all units with 'Software Engineering' in the UnitName.

(i) List all student information ordered by Surname with the
    Surname in CAPITALS.

(j) List only enrolments which have a Grade recorded.