SQL 员工表设计：创建、添加外键约束

CREATE TABLE employees ( employee_id INT PRIMARY KEY, first_name VARCHAR(50) NOT NULL, last_name VARCHAR(50) NOT NULL, email VARCHAR(100) UNIQUE, phone_number VARCHAR(20), hire_date DATE NOT NULL, job_id INT NOT NULL, salary DECIMAL(10,2), commission_pct DECIMAL(4,2), manager_id INT, department_id INT );

-- 添加外键约束 ALTER TABLE employees ADD CONSTRAINT fk_job_id FOREIGN KEY (job_id) REFERENCES jobs(job_id);

ALTER TABLE employees ADD CONSTRAINT fk_manager_id FOREIGN KEY (manager_id) REFERENCES employees(employee_id);

ALTER TABLE employees ADD CONSTRAINT fk_department_id FOREIGN KEY (department_id) REFERENCES departments(department_id);