BSCS : Database Management Systems 2 — Questions and Answers
Question 1: Which normal form eliminates transitive dependencies?
- 1NF
- 2NF
- 3NF (Correct answer)
- BCNF
Correct answer: 3NF
Third Normal Form (3NF) removes transitive dependencies, where a non-key attribute depends on another non-key attribute.
Question 2: In a B+ tree index, where are all data records (or pointers to them) stored?
- Root node only
- Internal nodes only
- Leaf nodes only (Correct answer)
- All nodes equally
Correct answer: Leaf nodes only
B+ trees store all data pointers exclusively in leaf nodes, with internal nodes holding only routing keys.
Question 3: Which SQL clause is used to filter groups after a GROUP BY?
- WHERE
- HAVING (Correct answer)
- FILTER
- GROUP FILTER
Correct answer: HAVING
HAVING filters rows after aggregation by GROUP BY, whereas WHERE filters rows before grouping.
Question 4: What does the 'D' in ACID stand for?
- Distributed
- Durability (Correct answer)
- Dependency
- Deletion
Correct answer: Durability
Durability guarantees that once a transaction commits, its changes persist even if the system crashes.
Question 5: A relation is in BCNF if for every non-trivial functional dependency X → Y, X is a:
- Candidate key (Correct answer)
- Primary key only
- Foreign key
- Super key only if X is minimal
Correct answer: Candidate key
BCNF requires that every determinant in any non-trivial FD must be a candidate (super) key of the relation.
Question 6: Which concurrency control technique uses timestamps to order transactions?
- Two-phase locking
- Timestamp ordering protocol (Correct answer)
- Optimistic concurrency control
- Multiversion concurrency control
Correct answer: Timestamp ordering protocol
The Timestamp Ordering Protocol assigns each transaction a timestamp and uses it to serialize conflicting operations.
Question 7: In the relational model, a tuple is analogous to a:
- Column
- Table
- Row (Correct answer)
- Index
Correct answer: Row
A tuple in relational theory corresponds to a single row in a table, representing one instance of an entity.
BSCS : Database Management Systems 2
Which normal form eliminates transitive dependencies?