The following OLD_NEW_TABLE trigger definition is equivalent to the OLD_TABLE, NEW_TABLE trigger definition that follows it in terms of functionality; however, the OLD_NEW_TABLE syntax eliminates a join between OLD_TABLE and NEW_TABLE in the subquery, which makes it more high-performing.
CREATE TRIGGER inventory_trigger AFTER UPDATE ON inventory REFERENCING OLD_NEW_TABLE AS OldNewTab (OldValue, NewValue) (INSERT INTO InventoryLogTbl SELECT OldValue.ProductKey, OldValue.AvailQty, NewValue.AvailQty FROM OldNewTab;); CREATE TRIGGER inventory_trigger AFTER UPDATE ON inventory REFERENCING OLD_TABLE AS OldTab NEW_TABLE AS NewTab (INSERT INTO InventoryLogTbl SELECT OldTab.ProductKey, OldTab.AvailQty, NewTab.AvailQty FROM OldTab, NewTab WHERE OldTab.ProductKey = NewTab.ProductKey;);