In the 3rd part of the question below:
Study the tables given below and write relational algebra expressions for the queries that follow.
STUDENT(+ROLLNO, NAME, AGE, GENDER, ADDRESS, ADVISOR) COURSE(+COURSEID, CNAME, CREDITS) PROFESSOR(+PROFID, PNAME, PHONE) ENROLLMENT(+ROLLNO, +COURSEID, GRADE)
Primary keys are preceded by a +. ADVISOR is a foreign key referring to PROFESSOR table. ROLLNO and COURSEID in ENROLLMENT are also foreign keys referring to THE primary keys with the same name.
- Names of femal students
- Names of male students along with advisor name
- Roll Number and name of students who have not enrolled for any course.
How do I represent NULL marks in relational algebra?
ROLLNO after assigning
ENROLLMENT table as
COURSEID = NULL
Is this valid?