从最小的部门寻找员工

Question

如何从员工人数最少的部门找到员工姓名列表？

员工的表结构是：

| eid | ename | department |

Answer 1

如果您希望部门员工人数最少，只需从员工表中选择行，然后按部门分组，以获取每个行的行数。您可以按升序对计数进行排序，并限制为1行以有效地获得最小值：

SELECT department, COUNT(*) AS numEmployees
FROM employees
GROUP BY department
ORDER BY numEmployees ASC
LIMIT 1;

然后，要获取该部门中所有员工的姓名，只需选择名称并将该子查询用作条件：

SELECT ename
FROM employees
WHERE department = (
   SELECT department
   FROM employees
   GROUP BY department
   ORDER BY COUNT(*) ASC
   LIMIT 1);