title: FOREIGN KEY SAME TABLE error - but foreign key doesn't exist
body: <p>I am trying to add a foreign key constraint which references the same table.</p>
  
  <pre><code>IF NOT EXISTS (SELECT * FROM sys.foreign_keys WHERE object_id = OBJECT_ID(N'[dbo].[FK_Documents_Parent]') AND parent_object_id = OBJECT_ID(N'[dbo].[Documents]'))
  BEGIN
      ALTER TABLE [dbo].[Documents]  WITH CHECK ADD  CONSTRAINT [FK_Documents_Parent] FOREIGN KEY(LinkedDocumentId)
      REFERENCES [dbo].[Documents] ([Id])
  END
  </code></pre>
  
  <p>The relationship <code>FK_Documents_Parent</code> does not exist.</p>
  
  <p>However, it throws the error:</p>
  
  <blockquote>
    <p>The ALTER TABLE statement conflicted with the FOREIGN KEY SAME TABLE constraint "FK_Documents_Parent". The conflict occurred in database "dev", table "dbo.Documents", column 'Id'.</p>
  </blockquote>