请问select max（level） as level1 count（distinct level1） from a
     group by subject
这样可以吗？

因为想把原来subject的值和level的值都保留了，不知如何写code

有人来讨论一下吗

data test;
input
subject  level;
cards;
1001     2
1001     3
1001     3
1001     2
1002     1
1002     3
1003     4
1003     4
1003     4
;
run;

proc sql;
   create table want as
   select test.*, count_max from test left join
      (
      select distinct subject, count(subject_level) as count_max
      from (select test.*, catx('_',subject,level) as subject_level from test)
      where subject_level in (select catx('_',subject,max(level)) as subject_level
                              from test group by subject)
      group by subject_level
      ) as temp
   on test.subject=temp.subject;
quit;

proc print;run;

先用select语句找出最大值a，再查询等于最大值a的观测有多少条，思路应该是这样的<br>