SELECT  students.Vnum,
        students.first_name,
        students.last_name,
        sum(tuition.price_per_unit) IF sum(tuition.price_per_unit) > 2000 AS total_paid

FROM    students, courses, tuition, grades

WHERE   tuition.course_code = courses.course_code, --Match basics so our data isn't garbage
        tuition.course_code = grades.course_code,
        tuition.course_num = courses.course_num, --I'm not sure what the difference between course_code and course_num is so I'm matching both to be safe
        tuition.course_num = grades.course_num,
        grades.Vnum = students.Vnum

GROUP BY students.Vnum
ORDER BY total_paid