附件

proc sql;
  select distinct date
        into :dlist separated by ' '
        from b_trans;
quit;

proc transpose data=b_trans out=a_trans1(drop=_label_ rename=(_name_=measure));
  by provider_id service_code;
        id date;
run;

data a_transx;
  if 0 then set b_trans(keep=provider_id service_code);
  length measure $8 &dlist 8;
  set a_trans1;  
        by provider_id service_code;
run;

运行有错误呀，最后那一段代码？
      
data a_transx;
  if 0 then set b_trans(keep=provider_id service_code);
  length measure $8 &dlist 8;
  set a_trans1;  
        by provider_id service_code;
run;
NOTE: Line generated by the macro variable "DLIST".
48          2019M07 2019M08 2019M09 2019M10 2019M11 2019M12 2020M01 2020M02 2020M03 2020M04 2020M05 2020M06 2020M07 2020M08 2020M09
            ____
            22
48       ! 2020M10 2020M11 2020M12 2021M01 2021M02 2021M03 2021M04 2021M05 2021M06 2021M07 2021M08 2021M09 2021M10 2021M11 2021M12
ERROR 22-322: Syntax error, expecting one of the following: a name, _ALL_, _CHARACTER_, _CHAR_, _NUMERIC_.  

352: LINE and COLUMN cannot be determined.
NOTE: NOSPOOL is on. Rerunning with OPTION SPOOL might allow recovery of the LINE and COLUMN where the error has occurred.
ERROR 352-185: The length of numeric variables is 3-8.
352: LINE and COLUMN cannot be determined.

转置前 format date MONYY7.;
再试试呢

format date MONYY7后，列的排序就不是按顺序来了。应该是 7/2020-6/2021. 可出来的结果 是 APR- 21 排在第一位了