Which normalization form ensures that every determinant in a relation is a candidate key?
- Boyce-Codd Normal Form (BCNF)
- First Normal Form (1NF)
- Second Normal Form (2NF)
- Third Normal Form (3NF)
Boyce-Codd Normal Form (BCNF) ensures that every determinant in a relation is a candidate key. This form goes beyond 3NF and addresses certain types of dependencies, making the database more robust and minimizing redundancy.
What is a foreign key constraint used for in a database table?
- Defines a link between a column in one table and a column in another table
- Enforces uniqueness in a column
- Ensures data in a column is not NULL
- Sets a default value for a column
A foreign key constraint in a database table is used to define a link between a column in one table and a column in another table. This establishes referential integrity, preventing inconsistent data by ensuring that values in the foreign key column match those in the referenced primary key column.
What are the implications of having a mandatory relationship in terms of data integrity?
- It allows for null values in foreign keys
- It doesn't impact data integrity
- It ensures that all related records are present
- It leads to referential integrity issues
Having a mandatory relationship ensures that all related records must be present, promoting data integrity. This constraint guarantees that every record in the "many" side is linked to a corresponding record in the "one" side, preventing orphaned or incomplete relationships.
The _______ diagram in UML represents the static view of a system.
- Activity
- Class
- Sequence
- Use Case
In UML, the Class diagram represents the static view of a system. It illustrates the structure of the system by showing classes, their attributes, and the relationships between classes. This diagram is essential for understanding the organization of objects in the system.
Scenario: An e-commerce platform has different types of customers, including regular users, premium members, and administrators. How can Generalization and Specialization be utilized to model these entities effectively?
- Administrators as a subtype of regular users
- Premium members inheriting attributes from regular users
- Regular users, premium members, and administrators as attributes of the customer entity
- Regular users, premium members, and administrators as separate entities
To model the entities effectively, representing regular users, premium members, and administrators as separate entities using Generalization and Specialization is suitable. Each entity can have its own specific attributes and behaviors, allowing for flexible and clear modeling of customer types.
How does a UNIQUE constraint contribute to maintaining data integrity?
- Allows NULL values in columns, ensuring flexibility
- Ensures that all rows in a table have a unique combination of values in specified columns
- Forces each row in a table to have a different primary key value
- Validates that foreign key values exist in the referenced table
A UNIQUE constraint ensures that all rows in a table have a unique combination of values in the specified columns. This helps maintain data integrity by preventing duplicate records, ensuring that each row is distinct based on the defined uniqueness criteria.
How does the concept of slowly changing dimensions (SCD) relate to fact tables?
- SCD is a technique used to update fact tables in real-time
- SCD is irrelevant in the context of fact tables
- SCD is only applicable to dimension tables, not fact tables
- SCD is used to handle changes in dimension attributes over time, impacting both dimension and fact tables
Slowly Changing Dimensions (SCD) are used to manage changes in dimension attributes over time. This is crucial in data warehousing for historical analysis. When changes occur in dimensions, it affects related fact tables as well. Understanding this relationship is vital for designing accurate and comprehensive data warehouses.
Reverse Engineering helps in understanding the structure and relationships within an existing database schema, facilitating _______.
- Code optimization
- Database documentation
- Schema modification
- System integration
Reverse Engineering helps in understanding the existing database schema by documenting its structure and relationships. This facilitates database documentation, making it easier for developers and database administrators to comprehend and work with the database.
_______ techniques reduce the size of data stored in a database by eliminating redundancy and using encoding schemes.
- Data Compression
- Data Encryption
- Data Indexing
- Data Sharding
Data Compression techniques aim to reduce the size of stored data in a database. This is achieved by eliminating redundancy and applying encoding schemes that represent the data in a more space-efficient manner. Data Compression is valuable for optimizing storage space and improving overall database performance.
UML focuses on _______ modeling, while SQL focuses on _______ modeling.
- Behavioral
- Object-oriented
- Procedural
- Relational
UML focuses on Object-oriented modeling, emphasizing the representation of objects, classes, and their relationships. On the other hand, SQL focuses on Relational modeling, dealing with tables, data integrity, and relationships between tables in a relational database.