Cannot perform a DML operation inside a query

Question

Dear all,
I have implemented the "Online Discussion Forum" of Steve Muench (Building Oracle XML Applications,ISBN:1-56592-691-9), and am trying to extend it by logging the queries and timing information inside the ForumSearch.Hits function (http://examples.oreilly.com/orxmlapp/orxmlapp_examples.zip).
That function is called as follow
SELECT ForumSearch.Hits(...) as HITS from DUAL
However, I am getting the ORA-14551.
That function opens a cursor and performs a select count() on a dynamic SQL, closes the cursor and returns the number of hits found.
The way i tried to extend it was to simply add the following line after the_cursor was closed.
insert into LOGGING values(the_count,response);
However, unfortunately I get the fatal error message
ORA-14551
I do understand that one shall not do an INSERT while doing a SELECT on the same table, however in this case I am doing a INSERT on another table ...
Puzzling enough, if I try to launch a DBMS_JOB for doing that insert I get a ORA-14551 as well.
I thought that by launching the DBMS_JOB I was going to uncouple the 2 events ...
Advice is appreciated.
Luca

Answer 1

As you discovered, Oracle will not allow you to directly manipulate the database within a select statement. Since the call to dbms_job actually inserts a row in a table, you just moved the DML to a different table. What you need to do is create a seperate procedure to do the logging, and call that in your function. Something like:
CREATE PROCEDURE logger (p_count IN NUMBER, p_reponse IN VARCHAR2) IS
PRAGMA AUTONOMOUS_TRANSACTION;
BEGIN
   INSERT INTO logging VALUES (p_count, p_response);
   COMMIT;
END;then, your function would look something like:
CREATE FUNCTION counter RETURN NUMBER IS
l_count NUMBER;
l_response VARCHAR2(10);
BEGIN
   SELECT COUNT(*) INTO l_rval
   FROM t;
   logger(l_count,l_reponse);
   RETURN l_count;
END;TTFN
John