GATE CSE - GATE 2017-2018 Questions and Answers

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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) Î _sname = (Ïƒ_{courseno=107 âˆ§ percent>90} (Registration â‹ˆ Students))

(III) {T|ÆŽSÏµ Students, ÆŽRÏµ Registration ( S.rollno=R.rollno âˆ§ R.courseno=107 âˆ§ R.percent>90 âˆ§T.sname=S.sname)}

(IV) {(S_N) | ÆŽS_RÆŽR_P ((S_R, S_N)Ïµ Students âˆ§ S_R, 107, R_P > Ïµ Registration âˆ§ RP>90)}

I, II, III and IV

I, II and III only

I, II and IV only

II, III and IV only

Answer : Option A

Explanation :

-NA-

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