title: Match 2 columns, but bring along all associated rows from the second column
body: <p>What is the easiest way for Example1 to be converted to Example2 (I would be doing this with much longer lists)? Column C and D shall be associated to Col B for the output of Example2. This is not just to make Col B replicate Col A, although that is part of the solution. Thank you in advance!</p>
  
  <p>Example1:</p>
  
  <pre><code>Col A  Col B  Col C  Col D
  a      e       d       c
  l      l       o       a
  e      x       g       t 
  x      a       s       s
  </code></pre>
  
  <p>Example2:</p>
  
  <pre><code>Col A Col B  Col C  Col D
  a     a      s       s
  l     l      o       a
  e     e      d       c
  x     x      g       t
  </code></pre>