Nico,

You may be interested in reading the following article as Claudio's
site...
http://www.cvalde.com/document/declaRefIntegVsTrig.htm


Just remember what Helen had to say about performance problems with
FKs for lookup tables - perhaps also remembering my own little
addition that those performance problems are usually only important if
you are dealing with high volume tables. (I think anything over about
10-20 thousand records should be considered high volume in this
regard, although it all depends on how the table and FKs are used.)


Geoff Worboys
Telesis Computing