title: NHibernate map to inconsistent Data
body: <p>I am using NHibernate to map a DataModel. Unfotunatley the DataBase contains some inconsistent data due to lack of keys/constraints. Currently I am stuck with an m:n mapping where some keys on the map Table reference missing data.
  Here is some sample Data:</p>
  
  <pre><code>Table: Foo
  id  Value
  0   A
  1   B
  2   C
  
  Table: Bar
  id  Value
  10  X
  20  Y
  30  Z
  
  Table: Map
  foo_id  bar_id  amount
    0       10        2
    0       11        4
    1       12        5
    2       20        8
  </code></pre>
  
  <p>I want to fetch all the Foo, that also have a Bar. In (T)SQL i would just use a join. I've tired a couple of mappings (like references + nullable, etc), but since the mapping table contains a key, NHiernate seems to expect an entity.</p>
  
  <p>Any suggestions?</p>