mysql 生成不重复订单号

CREATE TABLE orders (
    order_id INT AUTO_INCREMENT PRIMARY KEY,
    order_number VARCHAR(255) NOT NULL,
    order_date DATETIME NOT NULL
);

INSERT INTO orders (order_number, order_date) VALUES ('ORD12345', NOW());

CREATE TABLE orders (
    order_id CHAR(36) PRIMARY KEY,
    order_number VARCHAR(255) NOT NULL,
    order_date DATETIME NOT NULL
);

INSERT INTO orders (order_id, order_number, order_date) VALUES (UUID(), 'ORD12345', NOW());

CREATE TABLE orders (
    order_id VARCHAR(255) PRIMARY KEY,
    order_number VARCHAR(255) NOT NULL,
    order_date DATETIME NOT NULL
);

INSERT INTO orders (order_id, order_number, order_date) VALUES (CONCAT(DATE_FORMAT(NOW(), '%Y%m%d%H%i%s'), LPAD(FLOOR(RAND() * 1000), 3, '0')), 'ORD12345', NOW());