I have a sql server db and have a question regarding foreign key indices.
Here's a snippet from the db:
In programme_affiliates, I have a computed field, this is always set to '2' in this instance.
The reason for it is that it maintains integrity between programmes and programmes_affiliates.
I also have a link to programme_types to ensure that '2' is always valid as a programme type.
I believe that you should always provide an index for a foreign key, but as it is a calculated fixed field, is this necessary in this case?