Page Reference MySQL RESTRICT style action

[DrQuincy]

From what I can tell if you have a Page Reference field and that links to a page, e.g.:

1. page1.pageReference links to page2
2. page2 is deleted
3. page1.pageReference now equals null

Is there any way here to mimic a MySQL RESTRICT action so that page2 cannot be deleted (and warns you as such in the admin) while there are page fields that point to it?

Thanks.

[Robin S]

Some hook code is here:

 

[DrQuincy]

Great, thanks!