编辑代码

CREATE DATABASE test;
use test;
create table datafrog_test1
(userid varchar(20),
changjing varchar(20),
intime varchar(20)
);

insert into datafrog_test1 values
(1,1001,1400),
(2,1002,1401),
(1,1002,1402),
(1,1001,1402),
(2,1003,1403),
(2,1004,1404),
(3,1003,1400),
(4,1004,1402),
(4,1003,1403),
(4,1001,1403),
(4,1002,1404),
(5,1002,1402),
(5,1002,1403),
(5,1001,1404),
(5,1003,1405);
 
SELECT concat(userid,'-',group_concat(distinct changjing order by intime SEPARATOR '-')) as a FROM (
    select *, @rank:=(case when @user=userid then @rank+1 else 1 end) as rn,
    @user:=userid from datafrog_test1,(
        select @user:=null, @rank:=0
    )as a
    order by userid, intime
) as aa
where rn<=2
group by userid;