1. Which of the following statements is (are) correct?

• a) Phsical level abstraction describes how a record is stored.
• b) View level abstraction hides details of data types.
• c) Physical level abstraction describes data stored in a database and their relationships.
• d) Logical level abstraction defines the physical schema.

Answer :- a, b, 

2. Consider the following relations:

Subject (sid, sname, credit)
Faculty (fid, sid)
Which of the following is correct?

• a) RA₁ C RAz
• b) RAg C RAg
• c) RAI C RAg
• d) RA1 = RAg

Answer :- c) RAI C RAg

3. What does the following Relational Algebra expression return?

• a) All heights except the maximum height from Mountain relation.
• b) All heights except the minimum height from Mountain relation.
• c) Minimum height from Mountain relation.
• d) Maximum height from Mountain relation.

Answer :- d) Maximum height from Mountain relation.

4. Consider the relational schema PhoneBook (Name, PhoneNo, Location, LastCalled)

• Ankit 3222265783 Kolkata 15 Jul
• Shreya 3222265783 Delhi 16 Jul
• Ankit 2222586110 Delhi 16 Jul
• Shreya 2222586110 Kolkata 15 Jul

Answer :- c

5. Consider the relation Flight (FlightNo, Source, Destination, Duration) where {FlightNo} and {Source, Destination, Duration} are the 2 candidate keys. What is the possible num- ber of superkeys of Flight?

• a) 8
• b) 9
• c) 10
• d) 16

Answer :- b

6. Consider a truth table having the following columns P Q R= ((P V Q) – -P) S= ( (P V Q) – P) If the truth table, with all the values, is represented as a relational instance, which column(s) (attribute(s)) should be chosen as candidate keys?

• a) {P,R}
• b) {P,Q}
• c) {Q,R}
• d) {Q,S)

Answer :- b, c

7. Consider the following instance of ChatBox (SenderID, ReceiverID).

Answer :- b

8. Consider the following table:

Answer :- d

9. Consider the following table:

Answer :- c

10. Which of the following can be a candidate key for the following instance?

Answer :- b