DB2 allows for the creation of ________ to enforce complex data integrity rules.
- Constraints
- Stored Procedures
- Triggers
- Views
Constraints
What is the purpose of the NOT NULL constraint in DB2?
- NOT NULL constraint allows specifying a default value for a column when NULL is encountered.
- NOT NULL constraint automatically increments the column value when a new row is inserted.
- NOT NULL constraint ensures that a column cannot contain NULL values.
- NOT NULL constraint restricts the insertion of duplicate values in a column.
The NOT NULL constraint in DB2 ensures that a column cannot have NULL values, thereby enforcing data integrity and preventing unexpected behavior in applications that rely on non-null values for certain attributes. This constraint is essential for maintaining data consistency and avoiding errors related to NULL handling.
How does normalization help in reducing redundancy in a database?
- Enhances query performance
- Improves data security
- Increases data storage requirements
- Reduces data duplication
Normalization helps in reducing redundancy by organizing data into multiple related tables, thereby minimizing duplicate data entries. This leads to efficient storage utilization and improves data consistency and integrity.
What is the purpose of an Entity-Relationship Diagram (ERD) in DB2?
- To generate reports
- To manage user permissions
- To optimize SQL queries
- To visualize the structure of a database
An Entity-Relationship Diagram (ERD) is a visual representation of the data model that helps in understanding the relationships between different entities in a database. It aids in database design and ensures data integrity.
IBM Data Studio provides a user-friendly interface for ________ and managing DB2 databases.
- Designing
- Developing
- Monitoring
- Querying
IBM Data Studio is designed to assist developers in developing applications for DB2 databases. It provides tools and features for writing and debugging SQL queries, designing and modifying database schemas, monitoring database performance, and optimizing queries. Hence, it enhances developers' productivity by providing a comprehensive environment for all stages of application development, from design to deployment.
High cardinality columns in indexes in DB2 require special ________ considerations.
- Index creation
- Maintenance
- Query planning
- Storage
High cardinality columns in indexes in DB2 require special storage considerations. High cardinality columns contain many unique values, which may lead to increased storage requirements and indexing overhead.
How are cardinality and ordinality represented in an ERD?
- By altering entity shapes
- Through color-coding
- Using text labels
- Via symbols and notation
Cardinality and ordinality in an Entity-Relationship Diagram (ERD) are typically represented through symbols and notation. These symbols, such as crow's feet and lines, indicate the cardinality (i.e., the maximum and minimum number of instances of one entity that can be associated with another) and ordinality (i.e., the sequence or order of occurrences) between entities. By understanding these representations, database designers and developers can accurately depict the relationships between entities in the database schema.
What is the primary purpose of creating views in DB2?
- Define security constraints
- Optimize query performance
- Provide data redundancy
- Simplify complex queries
Views in DB2 are primarily used to simplify complex queries by presenting a subset of data from one or more tables. They can hide the complexity of underlying table structures and provide a simplified interface for users to access data.
How does DB2 handle data integrity issues caused by concurrent transactions?
- DB2 automatically aborts one of the conflicting transactions to resolve data integrity issues.
- DB2 creates duplicate copies of conflicting data to prevent data integrity violations.
- DB2 ignores data integrity issues caused by concurrent transactions and allows inconsistent results.
- DB2 resolves data integrity issues by using locks to control access to shared resources during concurrent transactions.
DB2 employs various concurrency control mechanisms, such as locking and isolation levels, to manage data integrity issues arising from concurrent transactions. By using locks, DB2 ensures that only one transaction can access a specific resource at a time, preventing conflicting updates and maintaining data consistency. Additionally, DB2 supports different isolation levels, allowing users to control the visibility of changes made by concurrent transactions to address consistency requirements.
How does DB2 ensure data integrity within databases?
- ACID properties, BASE properties, CAP theorem, No data integrity mechanisms
- Data redundancy, Data inconsistency, Data fragmentation
- Referential integrity, Constraints, Data validation rules
- Transactions, No support for transactions, Data replication
DB2 ensures data integrity through various mechanisms such as referential integrity, constraints, and data validation rules. Referential integrity constraints enforce relationships between tables to maintain data consistency, while constraints and validation rules define permissible data values and ensure data accuracy. By adhering to these principles, DB2 maintains the integrity and reliability of the stored data.