SQL and Tuple Calculus

Question

Q. Given the relational schema :

ENROLL (S#, C#, Section), S# is student number.

TEACH (Prof, C#, Section), C# is course number.

ADVISE (Prof, S#), Prof is Thesis advisor of S#

PRE-REQ (C#, pre-C#), pre-c# is prerequisite course.

GRADE (S#, C#, grade, year)

STUDENT (S#, Sname), Sname is student name.

Give queries expressed in SQL and tuple calculus.

(i) List of students taking courses with smith or jones.

(ii) List all students taking at least one course that their advisor teaches.

(iii) List those professors who teach more than one section of the same course.

(iv) List all students number and course number

(v) List the student number and course number who got grade A

Answer 1

1)select sname from student where In(select count(*) from enroll,teach where enroll.c#=teach.c# and teach.prof=smith or teach.prof=jones;

Comments

I can see that you have not given the field name in the where clause... also the second select will return the count, that cannot be put into where clause.. Please check once.

Regards,
Tushar

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can anyone say if the answer for 2) is right or not