Do I need an index on this? 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?
Go through this link:
http://blog.sqlauthority.com/2010/08/22/sql-server-computed-columns-index-and-performance/

Since all values are constant and same creating non clustered index will not help here.