mysql三张表联合查询

CREATE TABLE users (
    id INT PRIMARY KEY,
    name VARCHAR(255)
);

CREATE TABLE orders (
    id INT PRIMARY KEY,
    user_id INT,
    product_id INT
);

CREATE TABLE products (
    id INT PRIMARY KEY,
    name VARCHAR(255),
    price DECIMAL(10, 2)
);

SELECT users.name AS user_name, products.name AS product_name, orders.id AS order_id
FROM users
INNER JOIN orders ON users.id = orders.user_id
INNER JOIN products ON orders.product_id = products.id;

SELECT users.name AS user_name, products.name AS product_name, orders.id AS order_id
FROM users
LEFT JOIN orders ON users.id = orders.user_id
LEFT JOIN products ON orders.product_id = products.id;

SELECT users.name AS user_name, products.name AS product_name, orders.id AS order_id
FROM users
RIGHT JOIN orders ON users.id = orders.user_id
RIGHT JOIN products ON orders.product_id = products.id;