Invalid Number in an IN list

Question

This SQL statement works fine:
update catalogue_table set keywords = keywords||','||trim(lower('someword'))||',' where recid in (6037,6038,6039,6040);But I want users to be able to supply the new keyword and the identifiers of the records they want updated, dynamically. So I write a procedure. This version also works OK:
create or replace PROCEDURE keyword_add (p_recid_list IN VARCHAR2,
                       p_keyword IN VARCHAR2)
IS
  v_keyword varchar2(64);
  v_sql varchar2(2000);
BEGIN
  v_keyword := ','||lower(trim(p_keyword))||','; 
  v_sql := 'update catalogue_table set keywords = keywords||'''||v_keyword||''' where recid in ('||p_recid_list||')';
  execute immediate v_sql; 
  commit;
END; The user calls the procedure like so:
begin
  keyword_add(p_recid_list => '6037,6038,6039,6040',
                            p_keyword => 'someword');
end; ...and all works well. But I then get to thinking that I would prefer not to use dynamic SQL unless it's really called for, so I rewrite the code like this
create or replace PROCEDURE keyword_add (p_recid_list IN VARCHAR2,
                       p_keyword IN VARCHAR2)
IS
  v_keyword varchar2(64);
BEGIN
  v_keyword := ','||lower(trim(p_keyword))||','; 
  update catalogue_table set keywords = keywords||v_keyword where recid_id in (p_recid_list);
  commit;
END; ...and this time, using the exact same "calling code" as before, I simply get an ORA-01722 error ('invalid number'). Well, I know that the string '6037,6038,6039,6040' isn't a valid number, but it's not supposed to be! It's supposed to be a string list of numbers that are used as the basis of an IN comparison. The standalone SQL version works just fine with such a list being used to find numeric recids. Why won't my procedure's code work the same, please??
Any help in getting me to understand what I'm doing wrong would be much appreciated!

Answer 1

I figured the 'and' would be a giveaway
There wasn't an 'and'. I have the screenshot if you'd like to see it. In it's entirety, your post, to which I replied, read:
Hello, your p_recid_list can't work like that, check out:
http://forums.oracle.com/forums/thread.jspa?messageID=3557905&#3557905
Not an "and" in sight. And only one link.
Well, since you're asking for help, how about just a little humility ;)
There's nothing non-humble about pointing out that your rush to criticise me for only reading a 'snapshot' of the information was entirely misplaced and inappropriate. I read 100% of what you had posted. That you went back and "silently" added to your post doesn't put me in the wrong for not having read the second post you linked to. That second link wasn't there when I read your post! And neither was there an "and" that I should have taken mind-reading hints from.
As for humility, my original post clearly states that I'm doing something wrong, and I'd like guidance on putting it right. There's no claim from me that I'm a SQL genius, in other words, and I know better than most that my limitations are extensive.
But I still know how to read articles and threads to which I am pointed, and being criticised for not reading a link you hadn't put in your original post seems... well, a touch dishonest in my opinion.