A.2.13 Designing Relational Databases Notes

1. Relational databases are the backbone of modern data management systems.
2. They enable efficient storage, retrieval, and manipulation of structured data.

Key Components of Relational Databases

1. Tables:
   1. The fundamental building blocks of a relational database, where data is stored in rows and columns.
   2. Each table represents an entity (e.g., Students, Courses) and contains attributes (e.g., Name, Age).
2. Primary Keys: Unique identifiers for each record in a table, ensuring data integrity.
3. Foreign Keys: Attributes that establish relationships between tables by referencing primary keys in other tables.
4. Relationships: Connections between tables, such as one-to-many, many-to-many, or one-to-one.

Normalization

1. As discussed before, there are three forms:
   1. First Normal Form (1NF): Ensures that each attribute contains only atomic (indivisible) values.
   2. Second Normal Form (2NF): Requires that all non-key attributes are fully functionally dependent on the primary key.
   3. Third Normal Form (3NF): Ensures that no transitive dependencies exist, meaning non-key attributes depend only on the primary key.

Designing a Relational Database

Step 1: Identify Entities and Attributes

1. Determine the entities (e.g., Students, Courses) and their attributes (e.g., Name, Age).
2. Define the primary key for each entity.

Step 2: Establish Relationships

1. Identify the relationships between entities (e.g., Students enroll in Courses).
2. Use foreign keys to establish these relationships.

Step 3: Normalize the Data

1. Apply 1NF to ensure atomicity.
2. Apply 2NF to eliminate partial dependencies.
3. Apply 3NF to remove transitive dependencies.

Step 4: Implement the Database

1. Create Tables: Define the structure of each table, including attributes and data types.
2. Insert Data: Populate the tables with records.
3. Define Relationships: Use foreign keys to link tables.

Querying Relational Databases

1. Relational databases use Structured Query Language (SQL) to interact with data.
2. SQL allows users to query, insert, update, and delete information efficiently.

Basic SQL Commands

1. SELECT: Retrieves data from tables.
2. INSERT: Adds new records to tables.
3. UPDATE: Modifies existing records.
4. DELETE: Removes records from tables.

Advantages of Relational Databases

1. Data Integrity: Ensured through primary and foreign keys.
2. Scalability: Easily accommodates growing data.
3. Flexibility: Supports complex queries and relationships.
4. Security: Provides robust access control mechanisms.

Challenges and Considerations

1. Complexity: Designing a normalized database can be time-consuming.
2. Performance: Highly normalized databases may require more complex queries, impacting performance.
3. Maintenance: Regular updates and backups are essential to ensure data integrity.

Social and Ethical Implications

1. Data Privacy: Relational databases often store sensitive information, raising concerns about unauthorized access.
2. Data Security: Ensuring data is protected from breaches is critical.
3. Ethical Use: Organizations must use data responsibly, respecting user consent and privacy.