MySQL 8.0

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select version();


version()


8.0.19


create table student(student_id int,student_name char(1));

insert into student values(1,'A');
insert into student values(2,'B');
insert into student values(3,'c');
insert into student values(4,'D');
insert into student values(5,'E');
create table problem(student_id int,problem_id int);

insert into problem values(1,111);
insert into problem values(5,112);
insert into problem values(3,113);
insert into problem values(2,114);
insert into problem values(3,115);
insert into problem values(1,116);
insert into problem values(2,117);
insert into problem values(2,118);
insert into problem values(5,119);
insert into problem values(4,120);
insert into problem values(5,121);
select p.student_id,student_name,count(*) as no_of_prob,rank() over(order by count(*) desc) rk
from problem p join student s on p.student_id=s.student_id 
group by p.student_id,student_name order by count(*) desc


student_id
student_name
no_of_prob
rk


5
E
3
1

2
B
3
1

1
A
2
3

3
c
2
3

4
D
1
5


select student_id,student_name,no_of_prob from (
select p.student_id,student_name,count(*) as no_of_prob,rank() over(order by count(*) desc) rk
from problem p join student s on p.student_id=s.student_id 
group by p.student_id,student_name order by count(*) desc) a
where rk=1 or no_of_prob=1


student_id
student_name
no_of_prob


5
E
3

2
B
3

4
D
1