并于自定义函数的问题，请进来看看。谢谢

create or replace function getxindianjishudianzhi (strjiebie varchar2) return number
is
Result varchar2(5);
begin   case strjiebie
when '0' then Result := '6';
when '1' then Result := '0';
when '2' then Result := '2';
when '3' then Result := '9';
when '4' then Result := '5';
else Result := '7' ;
end case;

  return(Result);
end getxindianjishudianzhi;