title: linq to entities inheritance query problem
body: <p>I'm trying to perform a linq to entities query on a table that's inherited using <a href="http://msdn.microsoft.com/en-us/data/cc765425.aspx" rel="nofollow noreferrer">Table per Type</a>.</p>
  
  <p>The problem I'm having is that I can't get at the properties on the Inhertied table only the properties on the Base Table.</p>
  
  <pre><code>var qry = from i in _DB.BaseTable
  where i is catalogueModel.InheritedTable
  // Field Doesn't Exist
  // &amp;&amp; i.InheritedTableField == "Value"
  select i;
  </code></pre>
  
  <p>When I try to cast the Inherited Table to it's type...</p>
  
  <pre><code>var qry = from i in _DB.BaseTable
  where i is catalogueModel.InheritedTable
  &amp;&amp; (i as catalogueModel.InheritedTable).InheritedTableField  == "Value"
  select i;
  </code></pre>
  
  <p>...the code compiles but i get a cool error which reads</p>
  
  <blockquote>
    <p>Only text pointers are allowed in work
    tables, never text, ntext, or image
    columns. The query processor produced
    a query plan that required a text,
    ntext, or image column in a work
    table.</p>
  </blockquote>
  
  <p>I suppose my question is How are you supposed to access the properties of the Inherited tables in linq to entities when using <a href="http://msdn.microsoft.com/en-us/data/cc765425.aspx" rel="nofollow noreferrer">Table per Type</a>?</p>