Dot.Net: Discover Attributs on Properties Sample

Question:

How to discover attributes in a class?
I do I find all properties that are annotated with marker attribute?

Dot.Net:Create Attribut Sample

Question:

How do I create a custom attribute in dot.net?
Do you have a simple sample for attribute creation in c# / dot.net?

After restoring a database the owner has changed.

Question:

I restored a db from my production environment.
After that step certain things became strange. It was for example now impossible to install diagram support.
I always receive this error.