第四题：
####
create table a
(qq int,
game varchar(2));

insert into a
values
(10000,\'a\'),
(10000,\'b\'),
(10000,\'c\'),
(20000,\'c\'),(20000,\'d\');

-- drop table a;
select * from a;

select qq,
group_concat(game separator\'_\') as \'game\'
from a
group by qq;

######create table hahaha
select qq,
group_concat(game separator\'_\') as \'game\'
from a
group by qq;

select * from hahaha;