1. What is normalization in database design?
a) Organizing data in random order
b) Structuring data to eliminate redundancy and dependency
c) Adding random data to the database
d) None of the above
Answer: b) Structuring data to eliminate redundancy and dependency
Explanation: Normalization is the process of organizing data in a database efficiently. This involves structuring the database to minimize redundancy and dependency.
2. Which normal form ensures that there are no partial dependencies?
a) First Normal Form (1NF)
b) Second Normal Form (2NF)
c) Third Normal Form (3NF)
d) Fourth Normal Form (4NF)
Answer: c) Third Normal Form (3NF)
Explanation: Third Normal Form (3NF) eliminates transitive dependencies and ensures that there are no partial dependencies.
3. What is a functional dependency in a relational database?
a) A relationship between two attributes in a relation
b) A relationship between two tables
c) A relationship between primary and foreign keys
d) A relationship between two databases
Answer: a) A relationship between two attributes in a relation
Explanation: Functional dependency is a relationship between two attributes in a relation, where the value of one attribute uniquely determines the value of another attribute.
4. Which of the following is NOT a step in database query optimization?
a) Parsing and translation
b) Logical optimization
c) Physical optimization
d) Retrieval of data
Answer: d) Retrieval of data
Explanation: Query optimization involves steps such as parsing and translation, logical optimization, and physical optimization, but retrieval of data is not typically considered a step in optimization.
5. What is the purpose of decomposition in database design?
a) Combining multiple relations into one
b) Dividing a relation into smaller, more manageable relations
c) Removing all relations from the database
d) None of the above
Answer: b) Dividing a relation into smaller, more manageable relations
Explanation: Decomposition involves breaking down a relation into smaller, more manageable relations to achieve desirable properties such as minimizing redundancy and dependency.
6. Which concept ensures that decomposed relations can be recombined to form the original relation without loss of information?
a) Dependency preservation
b) Lossless join
c) Null valued tuples
d) Multivalued dependencies
Answer: b) Lossless join
Explanation: Lossless join ensures that decomposed relations can be recombined to form the original relation without any loss of information.
7. What is a disadvantage of using null values in a database?
a) Increased data integrity
b) Reduced storage space
c) Difficulty in querying data
d) None of the above
Answer: c) Difficulty in querying data
Explanation: Null values can introduce complexity in queries, as they require special handling to account for missing or unknown data.
8. Which normal form deals with multivalued dependencies?
a) First Normal Form (1NF)
b) Second Normal Form (2NF)
c) Third Normal Form (3NF)
d) Fourth Normal Form (4NF)
Answer: d) Fourth Normal Form (4NF)
Explanation: Fourth Normal Form (4NF) deals with multivalued dependencies, ensuring that a relation is free from certain types of redundancy arising from such dependencies.
9. What is the purpose of query optimization in database management?
a) To make queries more complex
b) To improve the efficiency of query execution
c) To increase database security
d) To introduce redundancy in the database
Answer: b) To improve the efficiency of query execution
Explanation: Query optimization aims to enhance the performance of query execution by minimizing the time and resources required to retrieve data.
10. Which algorithm is commonly used for optimizing join operations in a relational database?
a) Bubble Sort
b) QuickSort
c) Hash Join
d) Binary Search
Answer: c) Hash Join
Explanation: Hash Join is a commonly used algorithm for optimizing join operations in a relational database, especially for large datasets.
11. Which optimization method relies on educated guesses and rules of thumb?
a) Heuristic-based optimization
b) Cost estimation-based optimization
c) Random optimization
d) None of the above
Answer: a) Heuristic-based optimization
Explanation: Heuristic-based optimization relies on educated guesses and rules of thumb to improve query performance without exhaustively exploring all possible execution plans.
12. Which step of query optimization involves rearranging the query to reduce the number of operations required?
a) Parsing and translation
b) Logical optimization
c) Physical optimization
d) Execution plan generation
Answer: b) Logical optimization
Explanation: Logical optimization involves rearranging the query to reduce the number of operations required for execution, thereby improving performance.
13. Which normalization form deals with the elimination of repeating groups?
a) First Normal Form (1NF)
b) Second Normal Form (2NF)
c) Third Normal Form (3NF)
d) Boyce-Codd Normal Form (BCNF)
Answer: d) Boyce-Codd Normal Form (BCNF)
Explanation: Boyce-Codd Normal Form (BCNF) deals with the elimination of repeating groups and certain types of redundancy in a relation.
14. What is the primary goal of normalization in database design?
a) To maximize redundancy
b) To minimize data integrity
c) To minimize redundancy and dependency
d) None of the above
Answer: c) To minimize redundancy and dependency
Explanation: The primary goal of normalization is to minimize redundancy and dependency in a database, thereby improving data integrity and efficiency.
15. Which optimization method involves estimating the cost of different execution plans and selecting the most efficient one?
a) Heuristic-based optimization
b) Cost estimation-based optimization
c) Genetic algorithm optimization
d) None of the above
Answer: b) Cost estimation-based optimization
Explanation: Cost estimation-based optimization involves estimating the cost of different execution plans and selecting the most efficient one based on these cost estimates.
16. What is the key concept addressed by dependency preservation in database design?
a) Eliminating redundancy
b) Ensuring lossless join
c) Preserving relationships between attributes
d) None of the above
Answer: c) Preserving relationships between attributes
Explanation: Dependency preservation ensures that relationships between attributes, such as functional dependencies, are preserved during database design and manipulation.
17. Which algorithm is commonly used for optimizing select operations in a relational database?
a) Nested Loop Join
b) Merge Join
c) Sequential Scan
d) Index Scan
Answer: d) Index Scan
Explanation: Index Scan is commonly used for optimizing select operations in a relational database, especially for queries involving conditions on indexed columns.
18. What is the purpose of multivalued dependencies in database normalization?
a) To increase redundancy
b) To preserve dependency
c) To handle complex relationships between attributes
d) None of the above
Answer: c) To handle complex relationships between attributes
Explanation: Multivalued dependencies help in handling complex relationships between attributes by identifying dependencies that cannot be represented by functional dependencies alone.
19. Which optimization method involves using historical data and statistical models to estimate the cost of different execution plans?
a) Heuristic-based optimization
b) Cost estimation-based optimization
c) Random optimization
d) None of the above
Answer: b) Cost estimation-based optimization
Explanation: Cost estimation-based optimization involves using historical data and statistical models to estimate the cost of different execution plans and selecting the most efficient one.
20. What is the primary benefit of using functional dependencies in database normalization?
a) Increased redundancy
b) Improved data integrity
c) Decreased complexity
d) None of the above
Answer: b) Improved data integrity
Explanation: Functional dependencies help improve data integrity by enforcing rules about how attributes depend on each other, thereby reducing the risk of inconsistencies and anomalies in the database.