Relational Database Normalization Quiz

Study Notes

Relational Database

Database Normalization

Definition: Process of organizing data in a database to reduce redundancy and improve data integrity.
Normal Forms:
1. First Normal Form (1NF):
  - Eliminate duplicate columns from the same table.
  - Create separate tables for related data.
2. Second Normal Form (2NF):
  - Achieve 1NF.
  - Remove subsets of data that apply to multiple rows; create separate tables for them.
  - Ensure all non-key attributes are fully functional dependent on the primary key.
3. Third Normal Form (3NF):
  - Achieve 2NF.
  - Eliminate fields that do not depend on the primary key (transitive dependency).
4. Boyce-Codd Normal Form (BCNF):
  - A stronger version of 3NF; every determinant must be a candidate key.
Benefits:
- Reduces data redundancy.
- Enhances data integrity.
- Simplifies data maintenance.

Entity-relationship Models

Definition: A graphical representation of entities and their relationships in a database.
Components:
- Entities: Objects or things in the database (e.g., Customer, Order).
- Attributes: Properties of entities (e.g., Customer Name, Order Date).
- Relationships: Connections between entities (e.g., a Customer places an Order).
Types of Relationships:
- One-to-One (1:1): An entity in A is related to only one entity in B (e.g., each person has one passport).
- One-to-Many (1:N): An entity in A can relate to multiple entities in B (e.g., a customer can place many orders).
- Many-to-Many (M:N): Entities in A can relate to multiple entities in B and vice versa (e.g., students enrolled in courses).
Advantages:
- Visualizes complex data relationships.
- Facilitates database design and schema creation.

Data Integrity

Definition: The accuracy and consistency of data within a database.
Types:
- Entity Integrity: Ensures each table has a unique primary key; no null values in primary key columns.
- Referential Integrity: Ensures foreign keys correctly reference primary keys in related tables; maintains valid relationships.
- Domain Integrity: Enforces valid entries for a given attribute based on predefined rules (e.g., data type, format).
- User-Defined Integrity: Custom rules defined by users to maintain data integrity.
Importance:
- Protects data from corruption.
- Ensures reliable data retrieval and manipulation.
- Enhances data quality for analysis and reporting.

Database Normalization

Organizes data in a database to minimize redundancy and enhance integrity.
Normal Forms:
- First Normal Form (1NF): Eliminates duplicate columns; requires creation of separate tables for related data.
- Second Normal Form (2NF): Builds on 1NF; removes subsets of data applicable to multiple rows and ensures all non-key attributes depend fully on the primary key.
- Third Normal Form (3NF): Achieves 2NF; eliminates fields dependent on other non-key attributes (transitive dependency).
- Boyce-Codd Normal Form (BCNF): A stricter version of 3NF; requires every determinant to be a candidate key.
Benefits: Reduces redundancy, enhances integrity, and simplifies data maintenance.

Entity-Relationship Models

A diagrammatic representation of entities and their interactions in a database.
Components:
- Entities: Significant objects (e.g., Customer, Order).
- Attributes: Characteristics of entities (e.g., Customer Name, Order Date).
- Relationships: Links between entities (e.g., Customers placing Orders).
Types of Relationships:
- One-to-One (1:1): A unique correspondence between two entities (e.g., each person has one passport).
- One-to-Many (1:N): One entity can associate with many instances of another (e.g., a customer may place multiple orders).
- Many-to-Many (M:N): Both entities can have multiple associations (e.g., students enrolled in various courses).
Advantages: Clarifies intricate data relationships and aids in designing database schemas.

Data Integrity

Refers to the accuracy and consistency of data within a database.
Types:
- Entity Integrity: Guarantees each table possesses a unique primary key with no null values allowed.
- Referential Integrity: Validates that foreign keys correctly reference primary keys in other tables to maintain relationships.
- Domain Integrity: Ensures valid attribute entries based on predefined criteria (e.g., data type, format).
- User-Defined Integrity: Incorporates custom rules established by users for maintaining integrity.
Importance: Safeguards data from corruption, ensures reliable data retrieval, and improves quality for analysis and reporting.

Description

Test your knowledge on relational database normalization and entity-relationship models. This quiz covers the various normal forms, including 1NF, 2NF, 3NF, and BCNF, alongside their benefits. Understand how these principles reduce redundancy and improve data integrity in databases.