RDBMS Quiz

Normalization of a database is used to eliminate redundancy and improve efficiency.

A. Eliminate redundancy: This option is correct. One of the main goals of database normalization is to eliminate or reduce redundancy in order to improve data consistency and reduce storage requirements. Redundancy can lead to data inconsistencies and inefficiencies in data management.

B. Improve security: This option is not directly related to normalization. While normalization can indirectly improve security by ensuring data integrity and reducing the risk of data inconsistencies, it is not its primary purpose.

C. Improve efficiency: This option is correct. Normalization helps improve the efficiency of data storage, retrieval, and manipulation operations by organizing data into properly structured tables and reducing data redundancy. This can lead to faster and more efficient query execution.

D. Minimize errors: This option is partially correct. Normalization can help minimize errors by reducing redundancy and ensuring data consistency. However, it is not its sole purpose, as efficiency and elimination of redundancy are also important goals.

Therefore, the correct answer is:

A. Eliminate redundancy.

Functional dependencies generalize the concept of key dependencies in database normalization theory. A key dependency is a special case where the determinant is a candidate key. Option B (Relation dependencies) and C (Database dependencies) are not standard theoretical concepts in this context. Option D cannot be correct because A is specifically right, and E is unnecessary since A is valid.

Manager's salary hidden from employees exemplifies external level data hiding in the three-level database architecture. The external level (view level) provides different users with customized views of the same data - employees see their own data but not managerial salaries. Conceptual level describes the entire database structure, while physical level deals with storage details. The restriction is enforced at the external/view layer.

A compound key is made up of multiple pieces of information (attributes) that together uniquely identify an item in a list. Option A correctly states it's made of several pieces. Option B correctly states it uniquely identifies an item. Option C incorrectly says 'combination of each unique key' - compound keys combine attributes, not other keys. Therefore D (both A and B) is correct.

A database schema describes the complete structure: data elements (fields/attributes), records and files (tables/entities), and the relationships between records (foreign keys, associations). Option D captures all three aspects comprehensively. Options A, B, and C are each partially correct but incomplete individually. The schema is the blueprint defining all these elements together.

DBMS can import/export data to various external applications including spreadsheets (Excel), word processors (Word for reports), and graphics programs (for visualization). Option D correctly identifies all these as valid data transfer targets. The DBMS acts as a central data repository that can exchange information with diverse applications in the enterprise ecosystem.

ACID properties are fundamental to database transactions. Atomicity ensures all operations in a transaction succeed or fail together. Consistency maintains data validity, Isolation prevents concurrent transaction interference, and Durability guarantees committed data persists even after system failure.

Platform independence means software can run on multiple operating systems without modification. Scalability refers to handling increased load, robustness means stability under stress, and distributed involves multiple machines. A DBMS running on different operating systems is platform independent.

MySQL is the most widely used open source DBMS globally. Microsoft SQL Server and Oracle are commercial proprietary databases, while Microsoft Access is a desktop database product. Open source means the source code is freely available for modification and distribution.

A 3-tier system separates concerns into three layers: data storage (database), business logic, and client interface (presentation). 2-tier combines client directly with database, 4-tier adds an additional layer, and N-tier extends beyond three layers. The question describes the classic 3-tier architecture.