>http://en.wikipedia.org/wiki/Unique_key
>
>From the entry: "Depending on its design, a table may have arbitrarily many unique keys but at most one primary key."
>
Thanks a lot for the link. From this link I see also

Unique keys as well as primary keys can be referenced by foreign keys.

In any case, now I'm not clear what to do - I can not change all existing tables, but using name as a PK doesn't sound like a good idea to me.