oracle 判断字符是否为字母

create or replace function ischar(chr varchar2) return varchar2 is
  ischr varchar2(5);
begin
  select case
           when ascii(chr) between 65 and 122 THEN
            ‘true‘
           else
            ‘false‘
         end
    into ischr
    from dual;
  return ischr;
end;

原文：http://blog.csdn.net/cxx504659987/article/details/39666907