I can't seem to find an example of how to add restrictions to the where clause of an updateable view created via the rule system. For example I don't want the update to complete if a where clause is missing entirely, and in some cases I want to only allow the update if the where clause specifies a particular column.
Is there a way to do this?
Quick answer no.
Long answer. You can limit which fields can be updated and indeed rename fields or update completely different tables using rules and/or triggers. But you not can say that the where clause must include something.