前五道题：LeetCode 高频 SQL 50 题（基础版）之 【连接】部分 · 上
题目：577. 员工奖金
题解：
select r.name,b.bonus from Employee r left join Bonus b on r.empId=b.empId
where b.bonus <1000 or b.bonus is null
题目：1280. 学生们参加各科测试的次数
题解：
select stu.student_id student_id, stu.student_name student_name,sub.subject_name subject_name,
count(ex.student_id) attended_exams
from Students stu
join Subjects sub
left join Examinations ex
on stu.student_id = ex.student_id and sub.subject_name = ex.subject_name
group by stu.student_id ,sub.subject_name
order by stu.student_id ,sub.subject_name
题目：570. 至少有5名直接下属的经理
题解：
select name from Employee
where id in (select managerId from Employeegroup by managerIdhaving count(managerId)>=5
)
题目：1934. 确认率
题解：
select s.user_id user_id, round( ifnull(avg(c.action='confirmed'),0),2) confirmation_rate from Signups s left join Confirmations c
on s.user_id = c.user_id
group by s.user_id
![[yolov11改进系列]基于yolov11引入感受野注意力卷积RFAConv的python源码+训练源码](http://pic.xiahunao.cn/[yolov11改进系列]基于yolov11引入感受野注意力卷积RFAConv的python源码+训练源码)
)
![nginx: [emerg] bind() to 0.0.0.0:80 failed (10013: 80端口被占用](http://pic.xiahunao.cn/nginx: [emerg] bind() to 0.0.0.0:80 failed (10013: 80端口被占用)
