UGC NET · PAPER 2
UGC NET Paper 2 Computer Science – Unit 4: Database Management Systems PYQ (June 2023)
Q14. The total cost of retrieving records in sorted order using an unclustered B+ tree is (P = average number of records per data page, N = number of data pages, F = ratio of the size of a data entry to the size of a data record)
- (F × N) + P
- (F + P) × N
- F × N × P
- F + P/N
Q24. Let R(A, B, C, D) be a relational schema with functional dependencies A → B, B → C, C → D and D → B. The decomposition of R into (A, B), (B, C), (B, D)
- gives a lossless join, and is dependency preserving
- gives a lossless join, but is not dependency preserving
- does not give a lossless join, but is dependency preserving
- does not give a lossless join and is not dependency preserving
Q29. Consider the following statements:
A. A database design is in BCNF if each member of the set of relation schemas that constitutes the design is in BCNF.
B. A BCNF schema can have a transitive dependency.
C. It is always possible to obtain a 3NF design without sacrificing a lossless join.
D. There are multivalued dependencies in 4NF.
Choose the correct answer from the options given below:
A. A database design is in BCNF if each member of the set of relation schemas that constitutes the design is in BCNF.
B. A BCNF schema can have a transitive dependency.
C. It is always possible to obtain a 3NF design without sacrificing a lossless join.
D. There are multivalued dependencies in 4NF.
Choose the correct answer from the options given below:
- A, B and C only
- B, C and D only
- A, B and D only
- A, C and D only
Q36. Which of the following scenarios may lead to an irrecoverable error in a database system?
- A transaction writes a data item after it is read by an uncommitted transaction
- A transaction reads a data item after it is read by an uncommitted transaction
- A transaction reads a data item after it is written by a committed transaction
- A transaction reads a data item after it is written by an uncommitted transaction
Q51. Let R(A, B, C, D, E, F) be a relational schema with the functional dependencies C → F, E → A, EC → D, A → B. Which of the following is a key for R?
- CD
- EC
- AE
- AC
Q53. Which one of the following is NOT a part of the ACID properties of a database transaction?
- Atomicity
- Consistency
- Isolation
- Deadlock-freedom
Q61. Given the basic ER diagram and the relational model, which of the following is INCORRECT?
- An attribute of an entity can have more than one value
- An attribute of an entity can be composite
- In a row of a relational table, an attribute can have more than one value
- In a row of a relational table, an attribute can have exactly one value or a NULL value
Q63. Which of the following concurrency-control protocols ensures both conflict serializability and freedom from deadlock?
Statement I: Two-phase locking
Statement II: Timestamp ordering
Statement I: Two-phase locking
Statement II: Timestamp ordering
- Both Statement I and Statement II are correct
- Both Statement I and Statement II are incorrect
- Statement I is correct but Statement II is incorrect
- Statement I is incorrect but Statement II is correct