title: Foreign Key to multiple tables
body: <p>I've got 3 relevant tables in my database.</p>
  
  <pre><code>CREATE TABLE dbo.Group
  (
      ID int NOT NULL,
      Name varchar(50) NOT NULL
  )  
  
  CREATE TABLE dbo.User
  (
      ID int NOT NULL,
      Name varchar(50) NOT NULL
  )
  
  CREATE TABLE dbo.Ticket
  (
      ID int NOT NULL,
      Owner int NOT NULL,
      Subject varchar(50) NULL
  )
  </code></pre>
  
  <p>Users belong to multiple groups.  This is done via a many to many relationship, but irrelevant in this case.  A ticket can be owned by either a group or a user, via the dbo.Ticket.Owner field.  </p>
  
  <p>What would be the <em>MOST CORRECT</em> way describe this relationship between a ticket and optionally a user or a group?</p>
  
  <p>I'm thinking that I should add a flag in the ticket table that says what type owns it.</p>