多个表中一行的ID

CREATE TABLE users (
    user_id INT AUTO_INCREMENT PRIMARY KEY,
    username VARCHAR(255) NOT NULL,
    email VARCHAR(255) NOT NULL
);

CREATE TABLE orders (
    order_id INT AUTO_INCREMENT PRIMARY KEY,
    user_id INT,
    order_date DATE NOT NULL,
    total_amount DECIMAL(10, 2) NOT NULL,
    FOREIGN KEY (user_id) REFERENCES users(user_id)
);

INSERT INTO users (username, email) VALUES ('john_doe', 'john@example.com');
INSERT INTO orders (user_id, order_date, total_amount) VALUES (1, '2023-10-01', 150.75);

SELECT * FROM users WHERE user_id = 1;
SELECT * FROM orders WHERE user_id = 1;

-- 先插入用户数据
INSERT INTO users (username, email) VALUES ('jane_doe', 'jane@example.com');

-- 再插入订单数据，确保user_id存在
INSERT INTO orders (user_id, order_date, total_amount) VALUES (2, '2023-10-02', 200.50);