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Consider the following relational schema. Students(rollno: integer, sname: string) Courses(courseno: integer, cname: string) Registration(rollno: integer, courseno: integer, percent: real) Which of the following queries are equivalent to this query in English? "Find the distinct names of all students who score more than 90% in the course numbered 107" (I) SELECT DISTINCT S.sname FROM Students as S, Registration as R WHERE R.rollno=S.rollno AND R.courseno=107 AND R.percent > 90 (II) πsname(σcourseno=107 ∧ percent>90 (R registration ⋈ Students)) (III) { T | ∃S Students ∧ ∃R Registration ∧ (R.courseno=107 ∧ R.percent>90 ∧ T.sname=S.sname)} (IV) {<Sₙ> | ∃S, R, p (<S, Sₙ>∈Students ∧ <S, 107, R, p>∈Registration ∧ R > 90)}

1. I, II, III and IV
2. I, II and III only
3. I, II and IV only
4. II, III and IV only

Correct answer: I, II, III and IV

Solution

All four options accurately express the requirement to find distinct student names who scored above 90% in course 107, using different representations of relational algebra and SQL, thus confirming their equivalence.

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