oracle判斷字符是否為字母

oracle判斷字符是否為字母

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;