title: Performing a Parent then Child sort in Linq
body: <p>The intention is to sort the list by the parent, and then the child (there will only be one child).</p>
  
  <pre><code>Example Set:
  ID  ParentId Type   Unit
  1   NULL    Energy  kJ
  2   1       Cal
  3   NULL    Protein g
  4   NULL    Fat, total  g
  5   4       Saturated   g
  6   NULL    Carbohydrate    g
  7   6       Sugars  g
  8   NULL    Dietary fibre   g
  10  NULL    Sodium  mg
  11  NULL    Potassium   mg
  </code></pre>
  
  <p>So for example, if I sort by Type (alphabetical order) it would come up </p>
  
  <ol>
  <li>Carbohydrate</li>
  <li>Sugars (parent = 1.)</li>
  <li>Dietary fibre</li>
  <li>Energy</li>
  <li>Cal (parent = 4.)</li>
  <li>Fat, total</li>
  <li>Saturated (parent = 6.)</li>
  </ol>