title: FluentNHibernate - Map Foreign Key As Primary Key
body: <p>Hi I'm trying to migrate a database to ORM, and found a problem. The database was created with the concept of inheritance, where there is a parent table and several child tables who inherit their properties. To facilitate querys with INNER JOIN, all child tables contained only reference to the identification of the parent table (foreign keys that were at the same time are primary keys). Follows the model:</p>
  
  <pre><code>BaseDocument
  {
      Id : Long
      ...
  }
  
  AdministrativeDocument
  {
      Id : Long (PK), (FK : BaseDocument(Id))
      ...
  }
  
  PropositionDocument
  {
      Id : Long (PK), (FK : BaseDocument(Id))
      ...
  }
  
  ProjectDocument
  {
      Id : Long (PK), (FK : BaseDocument(Id))
      ...
  }
  </code></pre>
  
  <p>My question is: is there any way to create a mapping where a foreign key is also a primary key in FluentNHibernate with C#, or will I have to create separate primary keys for each table?</p>