declare 
v varchar2(2000):='1,2,3';
type t is table of number index by binary_integer;
tab t;
begin 

select cast(v as t) from dual ;

if tab.count>0 then 

dbms_output.put_line ('data converted');
end if;


end ;

SCOTT@orcl_12.1.0.2.0> declare
  2    v	 varchar2 (2000) := '1,2,3';
  3    type t is table of number index by binary_integer;
  4    tab	 t;
  5  begin
  6    select regexp_substr (v, '[^,]*', rownum)
  7    bulk collect
  8    into   tab
  9    from   dual
 10    connect by level <= regexp_count (v, ',') + 1;
 11    if tab.count > 0 then
 12  	 dbms_output.put_line (tab.count || ' rows of data converted');
 13    end if;
 14  end;
 15  /
3 rows of data converted

PL/SQL procedure successfully completed.