GATE Papers >> CSE >> 2013 >> Question No 35

Question No. 35 CSE | GATE 2013

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) $\prod_\mathrm{sname}({\mathrm\sigma}_{\mathrm{courseno}=107\;\wedge\;\mathrm{percent}>90}(\mathrm{Registration}\;\bowtie\;\mathrm{Students})$

(III) {T | ∃S Students, ∃ R Registration ( S.rollno=R.rollno ∧ R.courseno=107 ∧ R.percent>90 ∧T.sname=S.sname)}

(IV) {<SN> | ∃SR ∃RP ( <SR, SN> Students ∧ <SR, 107, RP> Registration ∧ RP>90)}


Answer : (A) I, II, III and IV


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