I have a form with a multi-row block based on a table. The requirement is that the user can only enter 1 row into the block at a time and commit it. They should not be allowed to create a second row before committing the first.

I tried using a WHEN-CREATE-RECORD trigger like this:

if :system.block_status = 'CHANGED' then
    alert('Can only create one record at a time');
end if;

However, this prevents me creating a new record even after committing changes.

One way would be to loop through all records and if the second record isn't null, alert the user.

DECLARE
    n_index NUMBER := 0;
BEGIN
    Go_block('block_name');

    first_record;

    WHILE :SYSTEM.last_record != 'TRUE' LOOP
        next_record;

        IF :block_name.item_name IS NOT NULL THEN --replace item_name with one which the user will enter all the time
          n_index := n_index + 1;
        END IF;

        IF n_index > 0 THEN
          Alert('Only one record can be created at a time!');
        END IF;
    END LOOP;
END;

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