Create trigger within PL/SQL

Question

I have a procedure that creates a trigger. When I execute the procedure I get an error: ORA-01031, however, when I copy and paste the create trigger command, it executes and will create the trigger without any problems. What is causing the 'insufficient privileges' error when it attempts to create it within a procedure?
Here is the stream of commands SQLPlus that shows what I am getting:
SQL> CREATE OR REPLACE PROCEDURE prc_create_trigger
2 (Table_Name in varchar2)
3 IS
4 v_create_trigger VARCHAR2(4000);
5 BEGIN
6 v_create_trigger := 'CREATE OR REPLACE TRIGGER trg_pauls_table ';
7 v_create_trigger := v_create_trigger || 'AFTER INSERT ON ' || table_name || ' ';
8 v_create_trigger := v_create_trigger || 'REFERENCING NEW AS newrow OLD AS oldrow FOR EACH ROW ';
9 v_create_trigger := v_create_trigger || 'DECLARE ';
10 v_create_trigger := v_create_trigger || ' v_text varchar2(20);';
11 v_create_trigger := v_create_trigger || 'BEGIN';
12 v_create_trigger := v_create_trigger || ' v_text := ''Inserted Row'';';
13 v_create_trigger := v_create_trigger || ' dbms_output.put_line(v_text);';
14 v_create_trigger := v_create_trigger || 'END;';
15
16 DBMS_OUTPUT.put_line(v_create_trigger);
17
18 --
19 execute IMMEDIATE v_create_trigger;
20 END;
21 /
Procedure created.
SQL> exec prc_create_trigger('pauls_table');
CREATE OR REPLACE TRIGGER trg_pauls_table AFTER INSERT ON pauls_table
REFERENCING NEW AS newrow OLD AS oldrow FOR EACH ROW DECLARE v_text
varchar2(20);BEGIN v_text := 'Inserted Row';
dbms_output.put_line(v_text);END;
BEGIN prc_create_trigger('pauls_table'); END;
ERROR at line 1:
ORA-01031: insufficient privileges
ORA-06512: at "BAAN.PRC_CREATE_TRIGGER", line 20
ORA-06512: at line 1
SQL> CREATE OR REPLACE TRIGGER trg_pauls_table AFTER INSERT ON pauls_table
2 REFERENCING NEW AS newrow OLD AS oldrow FOR EACH ROW DECLARE v_text
3 varchar2(20);BEGIN v_text := 'Inserted Row';
4 dbms_output.put_line(v_text);END;
5 /
Trigger created.
I am wanting to do this because I need to create this trigger dynamically when a table has been created. This trigger is simply for testing the procedure.
Thank you for your assistance.
Paul

Answer 1

Why does the application need to drop and re-create tables in the first place? What is the purpose of this "re-org"? If it accomplishes anything useful, it's likely that there is some flaw in the application architecture/ design/ implementation that could be fixed once to remedy whatever problem this drop & rebuild option attempts to solve. If there really is a need to reorganize a table regularly, could the application at least be modified to use one of the various approaches Oracle provides for this sort of thing?
The "re-org" process you're describing is, at best, a hack. A trigger on the TABLES_TO_BE_REORGED table that creates triggers on whatever table name was deleted from this table is, at best, a hack. Layering one hack on top of another is likely to cause lots of pain.
For one thing, a trigger cannot commit. But DDL implicitly commits before and after the DDL is executed. So you cannot create a trigger within another trigger. You could have a trigger that creates a job that later runs and creates the new trigger, but that's adding an extra layer of asynchronisity to a problem that is already likely over-engineered. You could also declare the trigger that creates the trigger to be an autonomous transaction, but that would cause horrible problems if the re-org process ever were to encounter and exception and have to roll back.
Justin