mysql三个表关联查表语句

SELECT 
    u.user_id,
    u.username,
    u.email,
    o.order_id,
    o.order_date,
    p.product_id,
    p.product_name,
    p.price
FROM 
    users u
INNER JOIN 
    orders o ON u.user_id = o.user_id
INNER JOIN 
    products p ON o.product_id = p.product_id;

-- 创建表
CREATE TABLE users (
    user_id INT PRIMARY KEY,
    username VARCHAR(50),
    email VARCHAR(100)
);

CREATE TABLE orders (
    order_id INT PRIMARY KEY,
    user_id INT,
    product_id INT,
    order_date DATE
);

CREATE TABLE products (
    product_id INT PRIMARY KEY,
    product_name VARCHAR(100),
    price DECIMAL(10, 2)
);

-- 插入示例数据
INSERT INTO users (user_id, username, email) VALUES
(1, 'Alice', 'alice@example.com'),
(2, 'Bob', 'bob@example.com');

INSERT INTO products (product_id, product_name, price) VALUES
(101, 'Laptop', 999.99),
(102, 'Smartphone', 499.99);

INSERT INTO orders (order_id, user_id, product_id, order_date) VALUES
(1, 1, 101, '2023-01-01'),
(2, 2, 102, '2023-01-02');

-- 关联查询
SELECT 
    u.user_id,
    u.username,
    u.email,
    o.order_id,
    o.order_date,
    p.product_id,
    p.product_name,
    p.price
FROM 
    users u
INNER JOIN 
    orders o ON u.user_id = o.user_id
INNER JOIN 
    products p ON o.product_id = p.product_id;