CREATE TABLE settings (
    id INT UNSIGNED AUTO_INCREMENT PRIMARY KEY,
    business_id INT UNSIGNED NOT NULL,
    setting_key VARCHAR(80) NOT NULL,
    setting_value VARCHAR(255) DEFAULT NULL,
    CONSTRAINT fk_settings_business FOREIGN KEY (business_id) REFERENCES businesses(id) ON DELETE CASCADE,
    UNIQUE KEY uniq_setting_per_business (business_id, setting_key)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;