Clustered index or 2 indexes on mostly read table

Question

Note: I use Entity Framework on SQL Server 2012, if it matters.

I have a mostly-read table, it's rarely updated. Database size is not a concern, speed is.

There is a standard PK ID field. In Selects, these two are always queried on

int PersonID
int NationID

Is it faster to query if I put an index on each individually, or a single NONCLUSTERED one on both like this:

 CREATE NONCLUSTERED INDEX IX_mytable_Nation_person ON dbo.mytable
  (
   NationId,
   PersonId
   ) WITH( STATISTICS_NORECOMPUTE = OFF, 
    IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON,  ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]

Answer 1

Depends on how you query.

If you have...

WHERE PersonID = ... AND NationID = ...

...use composite index.

---

If you have...

WHERE PersonID = ... OR NationID = ...

...use separate indexes.