31.  Student (schoolid, schrollno, sname, saddress) School (schoolid, schname, schaddress, schphone) Enrolment(schoolid schrollno, erollno, examname) ExamResult(erollno, examname, marks) What does the following SQL query output? SELECT schname, COUNT (*) FROM School C, Enrolment E, ExamResult R WHERE E.schoolid = C.schoolid AND E.examname = R.examname AND E.erollno = R.erollno AND R.marks = 100 AND S.schoolid IN (SELECT schoolid FROM student GROUP BY schoolid HAVING COUNT (*) > 200) GROUP By schoolid 
Discuss 
Answer: (d).nothing; the query has a syntax error

32.  Given the basic ER and relational models, which of the following is INCORRECT? 
Discuss 
Answer: (c).In a row of a relational table, an attribute can have more than one value

33.  Consider a join (relation algebra) between relations r(R)and s(S) using the nested loop method. There are 3 buffers each of size equal to disk block size, out of which one buffer is reserved for intermediate results. Assuming size(r(R)) < size(s(S)), the join will have fewer number of disk block accesses if 
Discuss 
Answer: (a).relation r(R) is in the outer loop

34.  Let E1 and E2 be two entities in an E/R diagram with simple singlevalued attributes. R1 and R2 are two relationships between E1 and E2, where R1 is onetomany and R2 is manytomany. R1 and R2 do not have any attributes of their own. What is the minimum number of tables required to represent this situation in the relational model? 
Discuss 
Answer: (b).3

35.  In a schema with attributes A, B, C, D and E following set of functional dependencies are given A → B A → C CD → E B → D E → A Which of the following functional dependencies is NOT implied by the above set? 
Discuss 
Answer: (b).BD → CD

36.  A database of research articles in a journal uses the following schema. (VOLUME, NUMBER, STARTPGE, ENDPAGE, TITLE, YEAR, PRICE) The primary key is (VOLUME, NUMBER, STARTPAGE, ENDPAGE) and the following functional dependencies exist in the schema. (VOLUME, NUMBER, STARTPAGE, ENDPAGE) > TITLE (VOLUME, NUMBER) > YEAR (VOLUME, NUMBER, STARTPAGE, ENDPAGE) > PRICE The database is redesigned to use the following schemas. (VOLUME, NUMBER, STARTPAGE, ENDPAGE, TITLE, PRICE) (VOLUME, NUMBER, YEAR) Which is the weakest normal form that the new database satisfies, but the old one does not? 
Discuss 
Answer: (b).2NF

37.  Which of the following relational query languages have the same expressive power? 1.Relational algebra 2.Tuple relational calculus restricted to safe expressions 3.Domain relational calculus restricted to safe expressions 
Discuss 
Answer: (d).I, II and III

38.  A Relation R with FD set {A>BC, B>A, A>C, A>D, D>A}. How many candidate keys will be there in R? 
Discuss 
Answer: (c).3

39.  What is the min and max number of tables required to convert an ER diagram with 2 entities and 1 relationship between them with partial participation constraints of both entities? 
Discuss 
Answer: (c).Min 2 and max 3

40.  Relation R has eight attributes ABCDEFGH. Fields of R contain only atomic values. F = {CH > G, A > BC, B > CFH, E > A, F > EG} is a set of functional dependencies (FDs) so that F+ is exactly the set of FDs that hold for R. How many candidate keys does the relation R have? 
Discuss 
Answer: (b).4
