Oracle 获取CLOB列的长度（以字节为单位）

create table plch_clob
(i int primary key, x clob);

begin
   for indx in 1 .. 1000 loop
      insert into plch_clob( i, x) values (indx, 'CLOB Row: ' || indx);
   end loop;
   
   commit;
end;

select i, DBMS_LOB.GETLENGTH(x) len
from plch_clob
order by i desc

create or replace function cloblengthb(p_clob in clob ) return number
as
  v_temp_blob BLOB;
  v_dest_offset NUMBER := 1;
  v_src_offset NUMBER := 1;
  v_amount INTEGER := dbms_lob.lobmaxsize;
  v_blob_csid NUMBER := dbms_lob.default_csid;
  v_lang_ctx INTEGER := dbms_lob.default_lang_ctx;
  v_warning INTEGER;
  v_total_size number := 0; -- Return total clob length in bytes
BEGIN
  IF p_clob is not null THEN
    DBMS_LOB.CREATETEMPORARY(lob_loc=>v_temp_blob, cache=>TRUE);
    DBMS_LOB.CONVERTTOBLOB(v_temp_blob, p_clob,v_amount,v_dest_offset,v_src_offset,v_blob_csid,v_lang_ctx,v_warning);
    v_total_size := DBMS_LOB.GETLENGTH(v_temp_blob);
    DBMS_LOB.FREETEMPORARY(v_temp_blob);
  ELSE
    v_total_size := NULL;
  END IF;
  return v_total_size;
end cloblengthb;
/

create table plch_clob
(i int primary key, x clob);

begin
   for indx in 1 .. 1000 loop
      insert into plch_clob( i, x) values (indx, 'éé CLOB Row: ' || indx);
   end loop;
   
   commit;
end;
/

select cloblengthb(x), dbms_lob.getlength(x) from plch_clob
where  rownum = 1;

                         CLOBLENGTHB(X)                   DBMS_LOB.GETLENGTH(X)
--------------------------------------- ---------------------------------------
                                     16                                      14