Dynamic function call in Forms PL/SQL [SOLVED]

Question

I have a 10G form, which has a dropdown list of values. Depending on the value selected, I look up a setup table which will tell me the name of the database package/function to call.
I then want to call that function with a bind IN parameter and then retrieve the function return value (which is a varchar2 containing message(s) as a stream of text) to display to the user.
I have searched high and low and cannot find a good example.
(a) forms_ddl doesn't seem to have the ability
(b) dbms_sql - some forums/blogs warn away from this due to db version dependencies
(c) exec_sql seems to be very basic and more aimed at odbc calls, rather than calls to native oracle db functions.
Here is example pseudo-code of what I am attempting to do on a WHEN-BUTTON-PRESSED trigger
DECLARE
v_Param1 VARCHAR2 := 'myInputValue';
v_FunctionName VARCHAR2 := 'MYDBPKG.MYFUNCTION';
v_DynamicSQL VARCHAR2;
v_Result VARCHAR2;
BEGIN
v_DynamicSQL := 'BEGIN :v_result:='||v_FunctionName||'('||chr(39)||v_Param1||chr(39)||')'; END';
Bind v_result variable;
execute dynamic sql;
message('the resulting text was <'||v_result||'>');
END;
Obviously, my code above has the function name hard-coded, but my real-life code would retrieve this function name from a database table, so I cannot call the function directly in the Forms PL/Sql.
where the db package/function looks like this:
create or replace package MYDBPKG as
function myfunction(I_Param VARCHAR2) return VARCHAR2;
end mydbpkg;
Anybody got a good example ?
Thanks
Alan
Edited by: Alan Lawlor on 11-May-2011 09:34

Answer 1

Alan Lawlor wrote:
(a) forms_ddl doesn't seem to have the ability
(b) dbms_sql - some forums/blogs warn away from this due to db version dependencies
(c) exec_sql seems to be very basic and more aimed at odbc calls, rather than calls to native oracle db functions.you forgot
(d): don't use dynamic SQL
As far as I am concerned (from the code I am exposed to) 99,9% of dynamic SQL code is at best used when there is no need for it and at worst it is impemented the most horrific way you can imagine. OK, this is not the entire truth: in 0,4% it is used when there is no need for it, and in the other 0,5% it is used wrong. And in the other 99% it is a combination of both: it is used when there is no need for it plus it is used wrong. So the very best thing you can do is to avoid dynamic SQL.
but my real-life code would retrieve this function name from a database tablePlease don't do that. This is one of the worst things to do. Forget about the fact that it is a big security hole and most certainly will trash the shared pool of the database and bringing your server down. Most important to developers is that it is a hell of a nightmare to maintain and a lot worse to debug.
So seriously think about if you want to go down the Dynamic SQL route.
cheers