drop table test111;
create table test111(
name varchar2(10),
class number,
grade number

)
select * from test111;

insert into test111 values('a',1,23);
insert into test111 values('b',213);
insert into test111 values('bb',213);
insert into test111 values('bbb',null);
insert into test111 values('c',2123);
insert into test111 values('d',2);
insert into test111 values('e',2,223);
insert into test111 values('r',2233);
insert into test111 values('t',273);
insert into test111 values('y',3,237);
insert into test111 values('u',4,2543);

select name,class,grade,sum(grade)over (partition by class order by grade desc) from test111

select name,dense_rank()over(partition by class order by grade desc) mm from test111

select name,to_char(wm_concat(grade) over (partition by class order by grade)) from test111

select name,row_number() over (partition by class order by grade) from test111

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