只返回漢字的函數

create or replace function get_chinese(p_name in varchar2) return varchar2
as
  v_code     varchar2(30000) := '';
  v_chinese  varchar2(4000)  := '';
  v_comma    pls_integer;
  v_code_q   pls_integer;
  v_code_w   pls_integer;
begin
  if p_name is not null then
     select replace(substrb(dump(p_name,1010),instrb(dump(p_name,1010),'ZHS16GBK:')),'ZHS16GBK: ','') into v_code from dual where rownum=1;
     for i in 1..length(p_name) loop
         if lengthb(substr(p_name,i,1))=2 then
            v_comma  := instrb(v_code,',');
            v_code_q := to_number(substrb(v_code,1,v_comma-1));
            v_code_w := to_number(substrb(v_code,v_comma+1,abs(instrb(v_code,',',1,2)-v_comma-1)));
            if v_code_q>=176 and v_code_q<=247 and v_code_w>=161 and v_code_w<=254 then
               v_chinese := v_chinese||substr(p_name,i,1);
            end if;
            v_code := ltrim(v_code,'1234567890');
            v_code := ltrim(v_code,',');
         end if;
         v_code := ltrim(v_code,'1234567890');
         v_code := ltrim(v_code,',');
     end loop;
     return v_chinese;
  else
     return '';
  end if;
end;