你这个问题没有看懂，这是sas程序语言？根据id 得到 x1最大值数据什么意思？
id是编号吧，x1才是数据，是把x1最大数据的排序出来然后对应的id排序么？一个ID对应一个x1数据，直接对x1排序不就行了？？用insight部分可以直接排序的

proc sql;
create table wanted_aaa as
select * from aaa
group by id
having x1=max(x1);
quit;

proc sql;
create table wanted_bbb as
select * from bbb
group by id,x1
having x2=max(x2);
quit;

BTW, 以第一个程序为例，如果对于同一个id，有两条相同的x1,并且两条相同的x1都是最大值，那么两条都会取到；第二个程序也是这样。如果只需要取一条，那么可以改成select distinct * from...

data _aaa; set aaa; by id; if last.id; run;
data _bbb; set bbb; by id x1; if last.x1; run;

proc sql;
        create table max1 as select id , max(x1) as max from aaa group by id;
        create table max2 as select id ,x1, max(x2) as max from bbb group by id,x1;
quit;

proc sort data=aaa;
        by id;
run;

proc sort data=aaa;
        by id x1;
run;



data max1;
        set aaa;
        by id;
        if last.id;
run;


data max2;
        set bbb;
        by id x1;
        if last.x1;
run;