Problem in calling procedure

Question

Hi,
I am having one control table for triggers which is storing the procedure name, triggering event, when the trigger should be fired and other informations. I am having a procedure for calling the triggers and I am passing the parameters to it for when the trigger should be fired which proc should be called etc.
Now the proc code look like this:
PROCEDURE call_trg (
when_fire VARCHAR2,
for_what VARCHAR2,
triggering_event VARCHAR2,
p_table_name VARCHAR2,
p_data_type VARCHAR2,
p_field_descr VARCHAR2,
p_field_id VARCHAR2,
p_emp_id VARCHAR2,
p_tran_type VARCHAR2,
p_before_dt DATE,
p_after_dt DATE,
p_before_val VARCHAR2,
p_after_val VARCHAR2,
p_object_id VARCHAR2,
p_object_descr VARCHAR2
IS
CURSOR cur_procs_obj
IS
SELECT procedure_name
FROM control_table
WHERE table_name = p_table_name
AND fire_indicator = when_fire
AND for_what_ind = for_what
AND triggering_event_indicator = triggering_event
AND enabled_ind = 'E'
AND procedure_name like '%obj%';
CURSOR cur_procs_dt
IS
SELECT procedure_name
FROM control_table
WHERE table_name = p_table_name
AND fire_indicator = when_fire
AND for_what_ind = for_what
AND triggering_event_indicator = triggering_event
AND enabled_ind = 'E'
AND procedure_name like '%dt%';
BEGIN
FOR procs IN cur_procs_dt
LOOP
IF p_data_type = 'DATE' THEN
EXECUTE IMMEDIATE 'begin ' || procs.procedure_name(p_field_descr,p_field_id,p_emp_id,p_tran_type,p_before_dt,p_after_dt,p_object_id,p_object_descr) || '; end;';
END IF;
END LOOP;
FOR proc IN cur_procs_obj
LOOP
IF p_data_type <> 'DATE' THEN
EXECUTE IMMEDIATE 'begin ' || proc.procedure_name(p_field_descr,p_field_id,p_emp_id,p_tran_type,p_before_obj_id,p_after_obj_id,p_before_val,p_after_val,p_object_id,p_object_descr) || '; end;';
END IF;
END LOOP;
END;
Here the procedure_name is storing the name of the procedure which require input parameter. But when I compiling this code its throwing error:
Error: PLS-00224: object 'PROCS.PROC_NAME' must be of type function or array to be used this way
I dont want to make it a function as that procedure inserts the record to some table. I am using this control table for firing of trigger in a defined sequence mentioned in control table. Please let me know How I can achieve this.
cant I call the procedure in the way I did by passing the parameters?
Thanks.

Answer 1

Just a word of caution, It is not advisable to run code, stored in relational tables, dynamically the way it seems you are planning to do.
There are significant maintenance issues you'll face from not knowing which code and where.
Karthick, one of the gurus on this forum, was attempting something similar last year and Ask Tom pointed out all the pitfalls from such an approach.
Read about it here;
http://asktom.oracle.com/pls/asktom/f?p=100:11:0::::P11_QUESTION_ID:1943344500346351703
You may think you'll be saving a few lines of code, but you'll spend hours and hours debugging!
Also, one final point, it seems as what you looking for is procedure overloading, which pl/sql does offer and this may be the way to go to satisfy your requirements;
http://download.oracle.com/docs/cd/B19306_01/appdev.102/b14261/subprograms.htm#i12352