LC 570至少有5名直接下属的经理Managers with at Least 5 Direct Reports　中等

Employee 表的 managerId 指向直属经理；找出直接下属至少 5 人的经理姓名。

思路 自连接 + GROUP BY + HAVING COUNT(*) >= 5。

SELECT E.name
FROM Employee E
JOIN Employee R ON R.managerId = E.id
GROUP BY E.id, E.name
HAVING COUNT(*) >= 5;

数据表：Employee　·　关键字：找出直接下属至少 5 人的经理姓名