**Course Title:** SQLite Mastery: Lightweight Database Management **Section Title:** SQLite Database Design and Normalization **Topic:** Designing a well-structured and efficient SQLite database schema. ### Introduction Designing a well-structured and efficient database schema is crucial for any database management system, including SQLite. A well-designed schema ensures data consistency, reduces data redundancy, and improves query performance. In this topic, we will discuss the key principles and best practices for designing a well-structured and efficient SQLite database schema. ### Understanding the Database Schema A database schema is the overall structure or organization of a database, including the relationships between different tables and data entities. It defines how data is stored, organized, and accessed within the database. ### Key Principles of Database Schema Design 1. **Separate Concerns**: Divide your schema into separate entities or tables, each representing a specific concern or domain. This makes it easier to manage and maintain the schema. 2. **Use Meaningful Table Names**: Use descriptive and concise table names that indicate the purpose or content of each table. 3. **Minimize Data Redundancy**: Avoid storing redundant or duplicate data in multiple tables. Instead, use relationships and foreign keys to link related data. 4. **Optimize Data Types**: Use the smallest and most efficient data types possible to store each column's data. 5. **Use Primary Keys and Foreign Keys**: Define primary keys to uniquely identify each row in a table and foreign keys to establish relationships between tables. ### Best Practices for Database Schema Design 1. **Keep it Simple**: Avoid unnecessary complexity in your schema design. Aim for a balance between simplicity and flexibility. 2. **Use Indexes Wisely**: Use indexes to improve query performance, but avoid over-indexing, which can slow down write operations. 3. **Use Views and Stored Procedures**: Views and stored procedures can simplify complex queries and improve data access. 4. **Plan for Future Changes**: Design your schema to be flexible and adaptable to future changes and growth. ### Designing a Well-structured SQLite Database Schema Here are some steps to follow when designing a well-structured SQLite database schema: 1. **Identify the Entities**: Identify the key entities or domains that will be represented in your database. 2. **Define the Tables**: Create separate tables for each entity or domain, with descriptive table names and columns. 3. **Establish Relationships**: Use foreign keys to establish relationships between related tables. 4. **Optimize Data Types**: Use efficient data types to store each column's data. 5. **Create Indexes**: Create indexes to improve query performance. ### Example: Designing a Simple E-commerce Database Schema Here's an example of designing a simple e-commerce database schema: ```sql -- Create the products table CREATE TABLE products ( id INTEGER PRIMARY KEY, name TEXT NOT NULL, description TEXT, price REAL NOT NULL, category_id INTEGER NOT NULL, FOREIGN KEY (category_id) REFERENCES categories (id) ); -- Create the categories table CREATE TABLE categories ( id INTEGER PRIMARY KEY, name TEXT NOT NULL ); -- Create the orders table CREATE TABLE orders ( id INTEGER PRIMARY KEY, customer_id INTEGER NOT NULL, order_date DATE NOT NULL, total REAL NOT NULL, FOREIGN KEY (customer_id) REFERENCES customers (id) ); -- Create the customers table CREATE TABLE customers ( id INTEGER PRIMARY KEY, name TEXT NOT NULL, email TEXT NOT NULL, address TEXT NOT NULL ); -- Create the order_items table CREATE TABLE order_items ( id INTEGER PRIMARY KEY, order_id INTEGER NOT NULL, product_id INTEGER NOT NULL, quantity INTEGER NOT NULL, FOREIGN KEY (order_id) REFERENCES orders (id), FOREIGN KEY (product_id) REFERENCES products (id) ); ``` ### Conclusion Designing a well-structured and efficient database schema is critical for any database management system, including SQLite. By following the key principles and best practices outlined in this topic, you can create a well-organized and scalable database schema that supports your application's needs. **What to Expect in the Next Topic**: In the next topic, we will discuss "Understanding transactions and SQLite's ACID properties" from the "Transactions and Data Integrity" section. This topic will cover the concepts of transactions, atomicity, consistency, isolation, and durability (ACID), and how they ensure data integrity in SQLite databases. **External Resources:** * [SQLite Documentation: SQL Syntax](https://sqlite.org/lang.html) * [W3Schools: SQL Tutorial](https://www.w3schools.com/sql/) **We encourage you to ask questions and leave comments if you have any doubts or need further clarification on this topic.**

-- Create the products table
CREATE TABLE products (
    id INTEGER PRIMARY KEY,
    name TEXT NOT NULL,
    description TEXT,
    price REAL NOT NULL,
    category_id INTEGER NOT NULL,
    FOREIGN KEY (category_id) REFERENCES categories (id)
);

-- Create the categories table
CREATE TABLE categories (
    id INTEGER PRIMARY KEY,
    name TEXT NOT NULL
);

-- Create the orders table
CREATE TABLE orders (
    id INTEGER PRIMARY KEY,
    customer_id INTEGER NOT NULL,
    order_date DATE NOT NULL,
    total REAL NOT NULL,
    FOREIGN KEY (customer_id) REFERENCES customers (id)
);

-- Create the customers table
CREATE TABLE customers (
    id INTEGER PRIMARY KEY,
    name TEXT NOT NULL,
    email TEXT NOT NULL,
    address TEXT NOT NULL
);

-- Create the order_items table
CREATE TABLE order_items (
    id INTEGER PRIMARY KEY,
    order_id INTEGER NOT NULL,
    product_id INTEGER NOT NULL,
    quantity INTEGER NOT NULL,
    FOREIGN KEY (order_id) REFERENCES orders (id),
    FOREIGN KEY (product_id) REFERENCES products (id)
);