Restrictions On Dropping An Ordering
If the specified ordering does not exist, the system aborts the drop request and returns an error to the requestor.
There are no restrictions on dropping an ordering. The system always honors a DROP ORDERING request whether it is referenced by a view, stored procedure, trigger, or macro.
However, for an ordering to be dropped, the UDT on which it is defined must not be used by any table in the system. There is no restriction on replacing an ordering definition, however, so if you only need to replace, but not drop, an ordering definition to correct or revise its definition, you should use the REPLACE ORDERING statement instead. See “CREATE ORDERING/ REPLACE ORDERING” on page 416.
The drop ordering operation succeeds even if the ordering is referenced by a view, stored procedure, trigger, or macro. However, if you attempt to use a view, stored procedure, trigger or macro that references a dropped ordering operation, the request aborts and returns an error to the requestor.