mysql列出最低薪金大于1500的各种工作及从事此工作的员工人数。4 列出部门名称和这些部门的员工信息同时列出那些没有员工的部门5 查询部门编号、部门名称、部门位置、部门人数。

4. 查询部门名称和这些部门的员工信息，同时列出那些没有员工的部门。

SELECT d.department_name, e.employee_name
FROM departments d
LEFT JOIN employees e ON d.department_id = e.department_id
ORDER BY d.department_name;

5. 查询部门编号、部门名称、部门位置、部门人数。

SELECT d.department_id, d.department_name, d.department_location, COUNT(e.employee_id) AS department_size
FROM departments d
LEFT JOIN employees e ON d.department_id = e.department_id
GROUP BY d.department_id, d.department_name, d.department_location;