ASCII字符串==>16进制串

create or replace function AscToHex(sIn IN varchar2)
RETURN varchar2
IS
sTmp varchar2(4000);
i integer;
BEGIN
i:=1;
stmp:='';
for i in 1..length(sIn) loop
   sTmp:=sTmp||trim(to_char(ascii(substr(sIn,i,1)),'XXXX'));
end loop;
return sTmp;
END;
/

16进制串==>ASCII字符串
要区分字符集，以中文字符为例，对于数据库字符集是中文，要保证能够正确转回来，要有所不同。

数据库字符集是中文

create or replace function HexToAsc(sIn IN varchar2)
RETURN varchar2
IS
sTmp varchar2(4000);
i integer;
x integer;
BEGIN
i:=1;
stmp:='';
loop
   exit when i>length(sIn);
   x:=to_number(substr(sIn,i,2),'XXXX');
   if x>128 then
     sTmp:=sTmp||chr(to_number(substr(sIn,i,4),'XXXX'));
     i:=i+4;
   else
     sTmp:=sTmp||chr(to_number(substr(sIn,i,2),'XXXX'));
     i:=i+2;
   end if;
  
end loop;
return sTmp;
END;
/

数据库字符集是英文

create or replace function HexToAsc(sIn IN varchar2)
RETURN varchar2
IS
sTmp varchar2(4000);
i integer;
BEGIN
i:=1;
stmp:='';
loop
   exit when i>length(sIn);
   sTmp:=sTmp||chr(to_number(substr(sIn,i,2),'XXXX'));
   i:=i+2;
end loop;
return sTmp;
END;
/

测试，如下：

SQL>select hextoasc(asctohex('你好ABC么')) from dual;
HEXTOASC(ASCTOHEX('你好ABC么'))
------------------------------------------
你好ABC么