Database Constraints | Create Table with Constraints MYSQL

-- create table User
CREATE TABLE `user` (
  `user_id` char(5) PRIMARY KEY,
  `user_name` varchar(255) NOT NULL,
  `user_phone` char(20) UNIQUE KEY NOT NULL,
  `user_email` varchar(255) UNIQUE KEY NOT NULL,
  `user_password` varchar(255) NOT NULL,
  `user_balance` int(12) NOT NULL,
  `user_status` enum('unvalid','validated','disabled') NOT NULL,
  `user_role` enum('customer','admin','cashier') NOT NULL
);

-- create table Product
CREATE TABLE `product` (
  `product_id` char(4) PRIMARY KEY,
  `product_name` varchar(255) NOT NULL,
  `product_price` int(11) NOT NULL,
  `product_amount` int(11) NOT NULL
);

-- create table Order
CREATE TABLE `order` (
  `order_id` char(15) PRIMARY KEY,
  `order_date` datetime NOT NULL,
  `order_payment` int(11) NOT NULL,
  `user_id` char(5) NOT NULL,
  FOREIGN KEY (`user_id`) REFERENCES `user` (`user_id`)
);

-- create table Order detail
CREATE TABLE `order_detail` (
  `order_detail_id` char(19) PRIMARY KEY,
  `order_detail_amount` int(11) NOT NULL,
  `product_id` char(4) NOT NULL,
  `order_id` char(15) NOT NULL,
  FOREIGN KEY (`product_id`) REFERENCES `product` (`product_id`),
  FOREIGN KEY (`order_id`) REFERENCES `order` (`order_id`)
);