Is there any concern in referencing a unique index from a foreign key table?
Using SQL Server 2008 R2
Please advise thanks
Copied from MSDN page,
The only difference between the first (primary key) option and the other two is that unique* constraints and indexes can be defined on nullable columns. Primary key columns have to be
* Note that there are some slight differences between these in SQL-Server (unique indexes offer some options that are not available with unique constraints): When should I use a unique constraint instead of a unique index?
For example, (as @gbn points), a unique index can be partial. But then, it can't be referenced by a FK.