许多列的生成类型

我有以下类型:

TYPE t_my_list is record(col1 VARCHAR2(4000),col2 varchar2(4000),col3 varchar2(4000));
Type  listOfString is table of t_my_list;

然后我进行批量收集:

EXECUTE IMMEDIATE v_stmt BULK COLLECT INTO v_ret;

如果我有20列呢?我认为这样做是没有意义的:

TYPE t_my_list is record(col1 VARCHAR2(4000),col2 varchar2(4000),....col20 varchar2(200);

如何构建类型?

更新 :

declare
  TYPE                         t_my_list is record(colX VARCHAR2(4000),colY varchar2(4000),ColZ varchar2(4000));
  Type                         listOfString  is table of t_my_list;
  v_stmt      VARCHAR2(32000) := 'SELECT col1, col2, col2 FROM table_TEST';
  v_ret                        listOfString  := listOfString ();

begin
   EXECUTE IMMEDIATE v_stmt BULK COLLECT INTO v_ret;
   --DBMS_OUTPUT.PUT_LINE('v_ret = '||v_ret.count);   
    for i in v_ret.first..v_ret.last loop
       DBMS_OUTPUT.PUT_LINE('colX: '||v_ret (i).colX||', colY: '||v_ret (i).colY||', ColZ: '||v_ret (i).ColZ);
       --will be done second EXECUTE IMMEDIATE taking as parameter ColX, ColY and ColZ
    end loop;
end;