title: Powerquery - appending the same table to itself using differing columns
body: <p>So I have a list of properties and a list of the next four servicing dates</p>
  
  <p>e.g:</p>
  
  <pre><code>Property| Last    | Next1 | Next2  | Next3  | Next4  |  
  123 Road| 01-2019 |03-2019| 05-2019| 07-2019| 09-2019|  
  444 Str | 01-2019 |07-2019| 01-2020| 07-2020| 01-2021|  
  </code></pre>
  
  <p>etc.</p>
  
  <p>I want to see:</p>
  
  <pre><code>Property | Date  
  123 Road | 01-2019  
  444 Str  | 01-2019  
  123 Road | 03-2019  
  123 Road | 05-2019  
  123 Road | 07-2019  
  444 Str  | 07-2019 
  </code></pre>
  
  <p>etc.</p>
  
  <p>In SQL this would be a union join, in powerquery. I think it's an append, but I'm not sure how to go about it. i.e. how to select columns from a table, then append a table with a different selection. I can append the full table easily, but not certain columns.</p>