Grades database: Tablename field1 | field2 |... one example row Courses cno | ctitle | csc226 | Introduction to Programming I | Classes term | lineno | cno | a | b | c | d | f96 | 1031 | csc226 | 90 | 80 | 65 | 50 | Students sid | fname | lname | minit | 1111 | Nandita | Rajshekhar | K | Enrolls sid | term | lineno | 1111 | f96 | 1031 | Components term | lineno | compname | maxpoints | weight | f96 | 1031 | exam1 | 100 | 30 | Scores sid | term | lineno | compname | points | 1111 | f96 | 1031 | exam1 | 90 | What should the primary and foreign keys be? Draw a ERD diagram.