Foreign key referencing a 2 columns primary key in SQL Server

Of course it’s possible to create a foreign key relationship to a compound (more than one column) primary key. You didn’t show us the statement you’re using to try and create that relationship – it should be something like:

ALTER TABLE dbo.Content
   ADD CONSTRAINT FK_Content_Libraries
   FOREIGN KEY(LibraryID, Application)
   REFERENCES dbo.Libraries(ID, Application)

Is that what you’re using?? If (ID, Application) is indeed the primary key on dbo.Libraries, this statement should definitely work.

Luk: just to check – can you run this statement in your database and report back what the output is??

SELECT
    tc.TABLE_NAME,
    tc.CONSTRAINT_NAME, 
    ccu.COLUMN_NAME
FROM 
    INFORMATION_SCHEMA.TABLE_CONSTRAINTS tc
INNER JOIN 
    INFORMATION_SCHEMA.CONSTRAINT_COLUMN_USAGE ccu 
      ON ccu.TABLE_NAME = tc.TABLE_NAME AND ccu.CONSTRAINT_NAME = tc.CONSTRAINT_NAME
WHERE
    tc.TABLE_NAME IN ('Libraries', 'Content')