Question

Consider the following relations:

Student(sID, surName, firstName, campus, email)

Course(dept, cNum, name)


Offering(oID, dept, cNum, term, instructor)


Took(sID, oID, grade)

Such as:

Offering[dept, cNum] ⊆ Course[dept, cNum]

Took[sID] ⊆ Student[sID]


Took[oID] ⊆ Offering[oID]

Answer the following query using relational algebra:

1. Give the Student number of all students who have taken the course number “343” by the department “CS”.
2. Find sID of all students who have earned some grade over 80 and some grade below 50.
3. Find the Terms when the course number “369” by the department “CS” was not offered.
4. Find the Department and course number of courses that have never been offered.

Answer 1

1)Give the Student number of all students who have taken the course number “343” by the department “CS”:

2)Find sID of all students who have earned some grade over 80 and some grade below 50

3)Find the Terms when the course number “369” by the department “CS” was not offered

4)Find the Department and course number of courses that have never been offered