title: Linq: Convert datatable rows to Dictionary<string, Dictionary<string, string>>
body: <p>I have a data table with columns "a", "b", "c". a and b are my lookup keys, and so I want to find c. </p>
  
  <p>I'd like to use linq to convert it to a <code>Dictionary&lt;a, Dictionary&lt;b, c&gt;&gt;</code> (or an ILookup) </p>
  
  <p>Is this possible?</p>
  
  <p>The closet workaround I can come up with is:</p>
  
  <pre><code>var lookup = resultTable.AsEnumerable().ToLookup(row =&gt; row["a"] &amp; row["b"], 
                                                 row =&gt; row["c"]);
  </code></pre>
  
  <p>and then I can concatenate a+b to use as the key. </p>
  
  <p>Is there a better way, or is this possibly faster anyways due to it being a simpler data structure?</p>