CREATE TABLE customers ( id SERIAL PRIMARY KEY, name VARCHAR(50), email VARCHAR(100) UNIQUE NOT NULL );
CREATE TABLE products ( id SERIAL PRIMARY KEY, name VARCHAR(100), price DECIMAL(10,2) );
CREATE TABLE orders ( id SERIAL PRIMARY KEY, customer_id INT REFERENCES customers(id), product_id INT REFERENCES products(id), quantity INT );
INSERT INTO customers (name, email) VALUES ('John Doe', '[email protected]'); INSERT INTO products (name, price) VALUES ('Laptop', 999.99); INSERT INTO orders (customer_id, product_id, quantity) VALUES (1, 1, 2);
SELECT customers.name, products.name, orders.quantity FROM orders JOIN customers ON orders.customer_id = customers.id JOIN products ON orders.product_id = products.id;