GATE | Gate IT 2008 | Question 72

Student (school-id, sch-roll-no, sname, saddress)
School (school-id, sch-name, sch-address, sch-phone)
Enrolment(school-id sch-roll-no, erollno, examname)
ExamResult(erollno, examname, marks)

What does the following SQL query output?

SELECT  sch-name, COUNT (*) 
FROM    School C, Enrolment E, ExamResult R 
WHERE   E.school-id = C.school-id 
AND 
E.examname = R.examname AND E.erollno = R.erollno 
AND 
R.marks = 100 AND S.school-id IN (SELECT school-id 
                                FROM student 
                                GROUP BY school-id 
                                 HAVING COUNT (*) > 200) 
GROUP By school-id 
 /* Add code here. Remove these lines if not writing code */ 

(A) for each school with more than 200 students appearing in exams, the name of the school and the number of 100s scored by its students
(B) for each school with more than 200 students in it, the name of the school and the number of 100s scored by its students
(C) for each school with more than 200 students in it, the name of the school and the number of its students scoring 100 in at least one exam
(D) nothing; the query has a syntax error

Answer: (D)

Explanation: In outer SQL query in SELECT sch-name is used where as in GROUP BY clause, school-id is used, that should be same as in SELECT clause.

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