How do I allow updates but prevent inserts

Question

Hi,
I have a block which is none base table and uses cursors to do manipulation on the underlying database.
I want to allow uses to edit existing fields, but prevent them from creating new ones. I thought a simple change in the property palate to set 'insert allowed' to 'no' and changing this value when the insert stuff from the cursor tkaes place would do the trick, but I get 'update not allowed' when I try to edit the fields.
Any ideas? I definately havn't set update allowed to no.
Thanks
Mark

Answer 1

If you mean that a field that already has a value can be updated, but a field that has no value yet cannot be updated, than set the update_allowed property dynamically.
If :item is null then
  set_item_property(item,update_allowed, FALSE);
else
  set_item_property(item,update_allowed, TRUE);
end if;