title: Power Query M loop table / lookup via a self-join
body: <p>First of all I'm new to power query, so I'm taking the first steps. But I need to try to deliver sometime at work so I can gain some breathing time to learn.</p>
  
  <p>I have the following table (example):</p>
  
  <pre><code>Orig_Item       Alt_Item    
  5.7             5.10
  79.19           79.60
  79.60           79.86
  10.10           
  </code></pre>
  
  <p>And I need to create a column that will loop the table and display the final <code>Alt_Item</code>. So the result would be the following:</p>
  
  <pre><code>Orig_Item       Alt_Item        Final_Item  
  5.7             5.10            5.10    
  79.19           79.60           79.86   
  79.60           79.86           79.86   
  10.10           
  </code></pre>
  
  <p>Many thanks</p>