我在一个表中有两个列，比如品牌和产品，那么如何防止在相同品牌中插入相同的产品呢？

CREATE TABLE products (
    id INT AUTO_INCREMENT PRIMARY KEY,
    brand VARCHAR(255) NOT NULL,
    product VARCHAR(255) NOT NULL,
    UNIQUE KEY unique_brand_product (brand, product)
);

INSERT INTO products (brand, product) VALUES ('Apple', 'iPhone');
INSERT INTO products (brand, product) VALUES ('Apple', 'iPhone'); -- 这将失败，因为组合已存在

CREATE TABLE products (
    id INT AUTO_INCREMENT PRIMARY KEY,
    brand VARCHAR(255) NOT NULL,
    product VARCHAR(255) NOT NULL,
    UNIQUE INDEX idx_unique_brand_product (brand, product)
);

INSERT INTO products (brand, product) VALUES ('Apple', 'iPhone');
INSERT INTO products (brand, product) VALUES ('Apple', 'iPhone'); -- 这将失败，因为组合已存在

try:
    cursor.execute("INSERT INTO products (brand, product) VALUES (%s, %s)", ('Apple', 'iPhone'))
    connection.commit()
except IntegrityError as e:
    print("Error: The combination already exists.")

UPDATE products 
SET brand = 'Samsung', product = 'Galaxy'
WHERE id = 1 AND NOT EXISTS (
    SELECT 1 FROM products WHERE brand = 'Samsung' AND product = 'Galaxy'
);