title: C# Linq with datatables - select from one table what does not exist in the other
body: <p>For example, I have two tables that look like this</p>
  
  <p>DATATABLE 1</p>
  
  <pre><code>COLA  |  COLB  |  COLC 
   1       123      321
   2       321      333
   3       222      232
  </code></pre>
  
  <p>DATATABLE 2</p>
  
  <pre><code>COLA  |  COLB  |  COLC 
   1       123      321
   2       321      333
  </code></pre>
  
  <p>I want to select only row 3 from table one. </p>
  
  <p>I want to be able to join the two tables together on the COLA ID, but then only select the rows from DATATABLE 1 that do noto exist in DATATABLE 2.</p>
  
  <p>How can I do this in LINQ?</p>
  
  <p>I would strongly prefer the results to be a datatable, or Ienumerable or something easy to change back into a datatable. if it's not possible i will manage.</p>