Oracle Forms: only iterate through selected records - database

Question

My Problem is the following:
I have a datablock based on a FROM_clause, querying relevant data from two tables. In the same datablock I have a checkbox to select rows, as a non-database item. When the user presses a button, it will insert certain information from those records into a table.
At the moment I'm looping through all the records, checking if the checkbox for this row is activated or not, depending on that doing the inserts. It all works fine, if the datablock only shows a few rows, or the user just selected some rows at the top of the list. (My loop iterates from FIRST_RECORD to LAST_RECORD, or until the amount of insert-operations is equal to the amount of selected rows).
But for most of the time, the datablock will show a few thousand records. If the user now selects some rows at the end of the list (like record #8000) my loop will (uselessly) iterate through thousands of records to insert just a few rows. It takes a lot of time and is just unnecessary.
I'm working with Oracle Form Builder 11g
How can I create a loop, that will only iterate though the records that are selected?
Any hints or code samples would be appreciated!

Answer 1

Generally if a block is likely to contain more than a few dozen records, I'll avoid looping over the records if at all possible. In the past I've solved this problem in two ways - pick which one suits you.
Store the checkbox values in a GTT, then query the GTT
Create a Global Temporary table, and base the checkbox on that GTT. When the user clicks the button, have the button trigger POST the values to the table; then, you can execute a SQL query against the GTT to find the selected values.
Store the selected rows in an array, then loop through the array
Add a trigger to the checkbox so that whenever it is checked or unchecked, a record with the relevant record number is added or removed from a PL/SQL array. You can then loop through this array which will be much faster than navigating through the block of records.

Answer 2

To help others who may be facing similar problems I want to post my solution.
I loosely based my implementation on this tutorial I found during my research.
I created a RecordGroup in the WHEN_NEW_FORM_INSTANCE Trigger and added all columns I needed to store:
declare
rg_name varchar2(40) := 'SELECTED';
rg_id recordgroup;
gc_id groupcolumn;
begin
/* Make sure the record group does not already exist. */
rg_id := find_group(rg_name);
/* If it does not exist, create it and add the
** necessary columns to it. */
if id_null(rg_id) then
rg_id := create_group(rg_name);
/* Add columns to the record group */
gc_id := add_group_column(rg_id, 'Barcode', number_column);
gc_id := add_group_column(..);
end if;
Then I changed my WHEN_CHECKBOX_CHANGED to add or remove the row from the RecordGroup depending on the value of the checkbox.
declare
row_no number;
rg_id recordgroup := find_group('SELECTED');
gc_id groupcolumn;
total_rows number;
barcode number;
begin
total_rows := get_group_row_count(rg_id);
if :block.checkbox = 1 then
/* Add selected row to the RecordGroup */
add_group_row(rg_id, end_of_group);
set_group_number_cell('SELECTED.BARCODE',
total_rows + 1,
:block.number_item);
else
/* Find selected row in RecordGroup and remove it */
for i in 1 .. total_rows loop
barcode := get_group_number_cell('SELECTED.BARCODE', i);
if :block.number_item = barcode then
row_no := i;
exit;
end if;
end loop;
delete_group_row('SELECTED', row_no);
end if;
end;
And in my WHEN_BUTTON_PRESSED Trigger it loops only through the selected rows, which are stored in the RecordGroup
declare
selected number;
row_no number;
begin
..
selected := get_group_row_count('SELECTED');
for j in 1 .. selected loop
begin
barcode := get_group_number_cell('SELECTED.BARCODE', j);
..
insert into (..);
commit;
exception
when others then
error_logging(..);
end;
end if;
delete_group_row('SELECTED', all_rows);
..
end;