mysql 无条件自然连接

SELECT *
FROM table1
NATURAL JOIN table2
WHERE table1.some_column = 'expected_value';

SELECT *
FROM table1
LEFT JOIN table2 ON table1.common_column = table2.common_column;

-- 创建示例表
CREATE TABLE employees (
    employee_id INT PRIMARY KEY,
    name VARCHAR(50),
    department_id INT
);

CREATE TABLE departments (
    department_id INT PRIMARY KEY,
    department_name VARCHAR(50)
);

-- 插入示例数据
INSERT INTO employees (employee_id, name, department_id) VALUES
(1, 'Alice', 1),
(2, 'Bob', 2),
(3, 'Charlie', 1);

INSERT INTO departments (department_id, department_name) VALUES
(1, 'HR'),
(2, 'Engineering');

SELECT *
FROM employees
NATURAL JOIN departments;