Once you create a data or control block, you can create items in that block at any time. Create items via the Object Navigator by inserting them under the desired block, or via the Layout Editor by drawing them on the desired canvas.
Keep in mind that a block is a logical, not a physical, container for items. The items in a block can be arranged in any layout and can be displayed on any canvas.
Before creating an item, decide in which block the item should be, and whether the item will be a data or a control item.
When an item is created in a data block, Oracle Forms assumes the item is a data item, and sets its Database Item property to Yes. Data items are automatically included in any SELECT, UPDATE, and INSERT statements issued to the database.
If the new item created is a control item in a data block, its Database Item property must be explicitly set to No.
When an item is created in a control block, that item is always a control item, regardless of how the item's Database Item property is set. (Because a control block is not associated with a database table, none of the items in a control block can be data items.)