要转换这段data step 为sql。
if substr(postal_code,1,1) in ('K','L','M','N','P') THEN PROVINCE='ON' ;
ELSE PROVINCE='XX';

想用下面when in (list of value)的方式但是报错：ERROR: Operand of WHEN clause 1 is not the same data type as the CASE operand.
case  substr(postal_code,1,1)       
          when in ('K','L','M','N','P')  THEN 'ON'
          ELSE 'XX'
          END AS PROVINCE


目前成功的方式如下：
proc sql;
   create table province as
   select *,
      case  substr(postal_code,1,1)       
          when 'K' then 'ON'
          when 'L' then 'ON'
          when 'M' then 'ON'
          when 'N' then 'ON'
          when 'P' then 'ON'
          ELSE 'XX'
          END AS PROVINCE
   FROM RATE ;
QUIT;