The schema for the database is illustrated in Figure$2$ that depicts a relational database schema that includes an indication of primary and foreign key constraints.

Note that the schema stores information about both ongoing and past classes for a course. Also note that no marks are recorded for any enrollment of an ongoing class, and that, for a past class, a mark is recorded for each of its enrollments. Finally, you may assume that each class has at least one enrollment.

Figure $2$ : Schema

$($a$)$ The number, name and department of each instructor who has taught in the past on Mondays.

$($b$)$ The number of instructors who are currently teaching CS$350.$

$($c$)$ The course number, course name and grade of each course completed by a student whose student number is $2234.$

$($d$)$ The number, name and year of each student who is not in his or her first year, who has a final grade of at most $90$ in every course that she$/$he has completed and who was not taught by a professor in the philosophy department $($including current courses$).$ Note: use department name $$Philosophy$.$

$($e$)$ The number, name and department of each professor who has no current teaching commitments on either Mondays or Fridays, sorted by department and then by the professor$$s name. Note: use full day names, e$.$g$.,$Monday$.$

$($f$)$ The course number, term and section number of each class taught in the past by some professor, together with the number and name of that professor.

$($g$)$ The course numbers and total enrollment of courses with total enrollment counts among the three lowest. $($Note that one possible result could be: $[$CS$448,120],[$CS$446,120],[$CS$341,105],[$CS$246,110].$ Also note that all classes, past and ongoing, need to be considered.$)$

$($h$)$ The number of different third year students in each section of each course taught by each professor in the current term. The result should include the professor number, professor name, course number and section, and should also be sorted first by the name of the professor, then by the professor number, third by the course number, and finally by section. $($Note that a section is identified by a term and a section number. Also assume that sorting by section means sorting by term and then by section number. The result will therefore have a total of six columns.$)$

$($i$)$ The minimum and maximum final grade for each class that was taught in the past by a professor in the statistics department. The result should include the number and name of the professor, and the course number, course name, term and section of the class. Note: use department name $$Statistics$.$

$($j$)$ The percentage of departments with professors who have never taught more than one class in the same term.