Dynamic Creation of Items in Runtime through Application UI

Question

We have a requirement where the Users wanted to have an option of creating an item dynamically. We developed and deployed a very simple application but the users want to have the flexibility of adding new columns (without vaildations and processing - just data) to some of the existing regions. They are not IT people and want a simple interface to add columns without IT involvement.
I thought of two options.
(a) To pre-create around 10 items in the table with column names as customize1...customize10 with varchar2(1000). Have a configuration table which stores the column names and Label. Create a Report based on a Pl/SQL function returning query, and using HTMLDB_ITEM to dynamically populate them. Iam not very keen about this approach as do not want to create unnecessary columns and have to do a lot of manual processing for the data manipulation.
a.1. Can we create a form (not a report) based on a pl/Sql function returning query.
(b) To have an interface which does an "Alter Table .... add column ...." to create the new column. In this case how can we include this column to an existing form. Can we use HTMLDB_ITEM to add (create) columns to an existing region?
(c) Any other suggestion ?
Would appreciate an answer on the way to go forward to this, and also to a.1.
Thanks

Answer 1

Hi Marc,
Thanks. I just tried something like this. Taking the EMP table example, (it doesn't matter which table), I created a region based on a Pl/Sql function returning SQL query
( I selected the vertical report template including nulls to display it like a form ) :
DECLARE
v_sql VARCHAR2(3000) ;
mn_idx NUMBER := 1 ;
BEGIN
v_sql := 'SELECT ' ;
FOR recs IN (SELECT * FROM ALL_TAB_COLUMNS WHERE TABLE_NAME = 'EMP' ORDER BY COLUMN_ID)
LOOP
v_sql := v_sql || 'HTMLDB_ITEM.TEXT(' || mn_idx || ',' ||
recs.column_name || ') ' || recs.column_name || ', ' ;
mn_idx := mn_idx + 1 ;
END LOOP ;
v_sql := SUBSTR(v_sql, 1, LENGTH(v_sql) -2) ;
v_sql := v_sql || ' FROM EMP WHERE EMPNO = 7369 ORDER BY 1 ' ;
RETURN v_sql ;
END ;
This allowed me to do my updates etc.., Then I created a button called 'Apply' and a process called 'update_changes' on button click and defined this:
DECLARE
v_sql varchar2(1000) ;
mn_ctr NUMBER := 1 ;
BEGIN
v_sql := 'BEGIN UPDATE EMP SET ' ;
FOR recs IN (select COLUMN_ID, COLUMN_NAME, DATA_TYPE
from all_tab_columns where table_name = 'EMP'
ORDER BY COLUMN_ID) loop
-- Make changes here if required- this is assuming 9 columns --
v_sql := v_sql || recs.column_name || ' = HTMLDB_APPLICATION.G_F0' || mn_ctr || '(1),' ;
mn_ctr := mn_ctr + 1;
end loop ;
v_sql := substr(v_sql, 1, length(v_sql) - 1) ;
v_sql := v_sql || ' WHERE EMPNO = 7369; END ;' ;
execute immediate (v_sql) ;
END ;
Since this is for example, I didn't include code for Checksum and hardcoded empno = condition and have provision for 9 columns. I made some changes and tried saving it and I was able to do it.
I altered the table to add a column / drop a column and when I relogin, Iam able to see the changes.
Can you tell me if there could be any drawbacks in this approach ?.