mysql的两个表合并

-- users表结构
CREATE TABLE users (
    id INT PRIMARY KEY,
    name VARCHAR(50),
    email VARCHAR(50)
);

-- orders表结构
CREATE TABLE orders (
    id INT PRIMARY KEY,
    user_id INT,
    product VARCHAR(50),
    amount DECIMAL(10, 2)
);

-- 内连接示例
SELECT users.name, orders.product, orders.amount
FROM users
INNER JOIN orders ON users.id = orders.user_id;

-- 左连接示例
SELECT users.name, orders.product, orders.amount
FROM users
LEFT JOIN orders ON users.id = orders.user_id;

-- 右连接示例
SELECT users.name, orders.product, orders.amount
FROM users
RIGHT JOIN orders ON users.id = orders.user_id;

-- 全连接示例（MySQL不直接支持全连接，但可以通过UNION实现）
SELECT users.name, orders.product, orders.amount
FROM users
LEFT JOIN orders ON users.id = orders.user_id
UNION
SELECT users.name, orders.product, orders.amount
FROM users
RIGHT JOIN orders ON users.id = orders.user_id;