title: array_diff / array_diff_assoc / array_diff_key not sure about what to use in this situation
body: <p>I have two arrays that have identical keys. I want to check array a against array b and return the the whole row of the array of a that is NOT in b. I am messing with all of them and can't get the desired results.
  my arrays look like this:</p>
  
  <pre><code>//array a
  Array
  (
  [0] =&gt; Array
      (
          [pid] =&gt; 457633
          [name] =&gt; Test
          [descr] =&gt; sample
          [creator] =&gt; 
          [datetime] =&gt; 
      )
  
  ) 
   //array b
   Array
    (
      [0] =&gt; Array
      (
          [pid] =&gt; 1234
          [name] =&gt; server
          [descr] =&gt; server
          [creator] =&gt; server
          [datetime] =&gt; server
      )
  
  [1] =&gt; Array
      (
          [pid] =&gt; 12343
          [name] =&gt; serv3er
          [descr] =&gt; ser3ver
          [creator] =&gt; se3rver
          [datetime] =&gt; serve3r
      )
  
  )
  </code></pre>
  
  <p>this is the result of when i array_diff_assoc(b, a)</p>
  
  <pre><code> Array
  (
  [1] =&gt; Array
      (
          [pid] =&gt; 12343
          [name] =&gt; serv3er
          [descr] =&gt; ser3ver
          [creator] =&gt; se3rver
          [datetime] =&gt; serve3r
      )
  </code></pre>
  
  <p>)</p>
  
  <p>but when i compare a to b it is blank.</p>
  
  <p>I would even like to go further only compare the first value of the array (pid in this case), and if its not in both return that a row</p>