Discussion Database Security and UML

Often, systems have only one level of security when it comes to databases. Imagine that someone is trying to add a name (which should be composed only of letters) to a database. The user mistakenly hits a number, and the system rejects the entry. Such security can be implemented at the database management system (DBMS) or the application level.

Where would you apply security? Justify your choice.

What are some alternative practices or standards of utilizing UML for the visual representation of systems?

When would you use UML over other standards?

When are other standards preferable?