proc sql;
   create table all4_2 as
   select  distinct raw1.* ,raw2.y
   from raw1 natural right join raw2
   on  raw1.subject = raw2.subject and
        raw1.visit = raw2.visit and
         raw1.date = raw2.date;
   quit;
出错：
  on  raw1.subject = raw2.subject and
        --
        22
        76
ERROR 22-322: 语法错误，期望下列之一: 名称, ;, (, ',', '.', ANSIMISS, AS, CROSS, EXCEPT, FULL, GROUP, HAVING, INNER,
              INTERSECT, JOIN, LEFT, NATURAL, NOMISS, ORDER, OUTER, RIGHT, UNION, WHERE.