Database Design Fundamentals

Good database design is crucial for building scalable and maintainable applications. Let's explore the key principles and best practices.

Normalization

Normalization eliminates data redundancy and improves data integrity:

First Normal Form (1NF)

• Each column contains atomic values
• No repeating groups

Second Normal Form (2NF)

• Must be in 1NF
• All non-key attributes depend on the entire primary key

Third Normal Form (3NF)

• Must be in 2NF
• No transitive dependencies

Entity Relationship Design

Entities

Represent real-world objects:

• User
• Product
• Order

Relationships

Define how entities relate to each other:

• One-to-One: User ↔ Profile
• One-to-Many: User → Orders
• Many-to-Many: Products ↔ Categories

Primary and Foreign Keys

CREATE TABLE users (
  id INT PRIMARY KEY AUTO_INCREMENT,
  email VARCHAR(255) UNIQUE NOT NULL,
  created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
);

CREATE TABLE orders (
  id INT PRIMARY KEY AUTO_INCREMENT,
  user_id INT,
  total DECIMAL(10,2),
  FOREIGN KEY (user_id) REFERENCES users(id)
);

Indexing

Indexes improve query performance:

-- Single column index
CREATE INDEX idx_email ON users(email);

-- Composite index
CREATE INDEX idx_user_date ON orders(user_id, created_at);

Data Types

Choose appropriate data types:

• Use VARCHAR for variable-length strings
• Use INT for whole numbers
• Use DECIMAL for monetary values
• Use TIMESTAMP for dates and times

Best Practices

1. Use meaningful names: user_id instead of uid
2. Be consistent: Use the same naming convention throughout
3. Avoid NULL values when possible
4. Plan for scalability: Consider future growth
5. Document your schema: Maintain clear documentation

Well-designed databases are the foundation of robust applications!