Mutating error : row level BEFORE UPDATE trigger

Question

Hi,
I had an issue on mutating terror(was trying to write a row level BEFORE update trigger), however i got it resolved after refering tom kytes web site. I thought i would share it with everyone, might be helpful for a few... Thanks!
I will be more than happy to learn on further better ways of resolving this issue.
Below I have posted the trigger that was causing this error and the work around for that issue, I created a package and three other triggers to replace row level BEFORE update trigger:
++trigger that was causing this issue:++
CREATE OR REPLACE TRIGGER C_F_BI
BEFORE INSERT ON CONTACT_FUNCTION FOR EACH ROW
declare
cursor function_code_cur ( cur_contact_id CONTACT.Contact_Id%type,
cur_function_type_code CONTACT_FUNCTION.Function_Type_Code%type)
is
select
cft.function_type_code,
cft.multiples_permitted
from
CONTACT_FUNCTION cf,
CONTACT c,
CONTACT_FUNCTION_TYPE cft
where
c.acct_id = (select acct_id from contact where contact_id = cur_contact_id)
and c.contact_id = cf.contact_id
and cf.function_type_code = cft.function_type_code
and cft.function_type_code = cur_function_type_code;
v_function_type_code contact_function_type.function_type_code%type;
v_multiples_permitted contact_function_type.multiples_permitted%type;
E_Multiples_Not_Permitted Exception;
begin
if not function_code_cur%isopen then
open function_code_cur(:new.contact_Id,:new.function_type_code);
end if;
loop
fetch function_code_cur into v_function_type_code, v_multiples_permitted;
exit when not function_code_cur%found;
end loop;
** if the fetch returns a v_multiples_permitted of 'Y' or no record is found, then it is
** ok to add the record. Otherwise raise an error because that function_type is already
** being used at the current acct.
if v_multiples_permitted = 'N' then
raise E_Multiples_Not_Permitted;
end if;
close function_code_cur;
EXCEPTION
when E_Multiples_Not_Permitted then
raise_application_error( -20001,'Multiples not allowed for function type ' ||
v_function_type_code || '. sqlerrm - ' || sqlerrm );
when others then
raise;
end;
++solution for above issue :++
create or replace package state_pkg
is
type ridArray_rec is record(rid rowid, cont_id number, cont_fn_type varchar2(20));
type ridArray is table of ridArray_rec index by binary_integer;
newRows ridArray;
empty ridArray;
end state_pkg;
create or replace trigger contact_function_bu1
before update on contact_function
begin
state_pkg.newRows := state_pkg.empty;
end;
create or replace trigger contact_function_bu2
before update ON CONTACT_FUNCTION FOR EACH ROW
DECLARE
I NUMBER:=0;
begin
I := state_pkg.newRows.count+1;
state_pkg.newRows( I ).rid := :new.rowid;
state_pkg.newRows( I ).cont_id := :new.contact_id;
state_pkg.newRows( I ).cont_fn_type := :new.function_type_code;
end;
create or replace trigger contact_function_bu
after update ON CONTACT_FUNCTION
declare
cursor function_code_cur ( cur_contact_id CONTACT.Contact_Id%type,
cur_function_type_code CONTACT_FUNCTION.Function_Type_Code%type,
rid2 rowid)
is
select
cft.function_type_code,
cft.multiples_permitted
from
CONTACT_FUNCTION cf,
CONTACT c,
CONTACT_FUNCTION_TYPE cft
where
c.acct_id = (select acct_id from contact where contact_id = cur_contact_id)
and c.contact_id = cf.contact_id
and cf.function_type_code = cft.function_type_code
and cft.function_type_code = cur_function_type_code
and cf.rowid = rid2;
v_function_type_code contact_function_type.function_type_code%type;
v_multiples_permitted contact_function_type.multiples_permitted%type;
E_Multiples_Not_Permitted Exception;
begin
for i in 1 .. state_pkg.newRows.count loop
if not function_code_cur%isopen then
open function_code_cur(state_pkg.newRows(i).cont_id, state_pkg.newRows(i).cont_fn_type, state_pkg.newRows(i).rid);
end if;
loop
fetch function_code_cur into v_function_type_code, v_multiples_permitted;
exit when not function_code_cur%found;
end loop;
** if the fetch returns a v_multiples_permitted of 'Y' or no record is found, then it is
** ok to add the record. Otherwise raise an error because that function_type is already
** being used at the current acct.
if v_multiples_permitted = 'N' then
raise E_Multiples_Not_Permitted;
end if;
close function_code_cur;
end loop;
EXCEPTION
when E_Multiples_Not_Permitted then
raise_application_error( -20001,'Multiples not allowed for function type ' ||
v_function_type_code || '. sqlerrm - ' || sqlerrm );
when others then
raise;
end;
/

Answer 1

It seems you could have solved the issue otherwise:
CREATE OR REPLACE TRIGGER c_f_bi
   BEFORE INSERT
   ON contact_function
   FOR EACH ROW
DECLARE
   v_function_type_code        contact_function_type.function_type_code%TYPE;
   v_multiples_permitted       contact_function_type.multiples_permitted%TYPE;
   e_multiples_not_permitted   EXCEPTION;
BEGIN
   BEGIN
      SELECT cft.function_type_code, cft.multiples_permitted
        INTO v_function_type_code, v_multiples_permitted
        FROM contact c, contact_function_type cft
       WHERE c.acct_id = (SELECT acct_id
                            FROM contact
                           WHERE contact_id = :NEW.contact_id)
         AND c.contact_id = :NEW.contact_id
         AND cft.function_type_code = :NEW.function_type_code;
   EXCEPTION
      WHEN NO_DATA_FOUND
      THEN
         v_function_type_code := :NEW.function_type_code;
         v_multiples_permitted := '?';
   END;
** if the query returns a v_multiples_permitted of 'Y' or no record is found, then it is
** ok to add the record. Otherwise raise an error because that function_type is already
** being used at the current acct.
   IF v_multiples_permitted = 'N'
   THEN
      RAISE e_multiples_not_permitted;
   END IF;
EXCEPTION
   WHEN e_multiples_not_permitted
   THEN
      raise_application_error (-20001,
                                  'Multiples not allowed for function type '
                               || v_function_type_code
                               || '. sqlerrm - '
                               || SQLERRM
   WHEN OTHERS
   THEN
      RAISE;
END;
/:p