查找所有员工的last_name和first_name以及对应的dept_name
查找所有员工的last_name和first_name以及对应的dept_name
http://www.nowcoder.com/questionTerminal/5a7975fabe1146329cee4f670c27ad55
最直观的LEFT JOIN和JOIN的区别
三表连接
SELECT e.last_name, e.first_name, d.dept_name FROM employees e LEFT JOIN (SELECT emp_no, dept_name FROM dept_emp LEFT JOIN departments ON dept_emp.dept_no = departments.dept_no) d ON e.emp_no = d.emp_no