title: Return single column from a multi-dimensional array
body: <p>I'm a novice at PHP and I need a quick solution to the following problem but can't seem to come up with one:</p>
  
  <p>I have a multi-dimensional array like so</p>
  
  <pre><code>Array
  (
      [0] =&gt; Array
          (
              [blogTags_id] =&gt; 1
              [tag_name] =&gt; google
              [inserted_on] =&gt; 2013-05-22 09:51:34
              [inserted_by] =&gt; 2
          )
  
      [1] =&gt; Array
          (
              [blogTags_id] =&gt; 2
              [tag_name] =&gt; technology
              [inserted_on] =&gt; 2013-05-22 09:51:34
              [inserted_by] =&gt; 2
          )
  )
  </code></pre>
  
  <p>I want to use the <code>implode()</code> to somehow return a comma-separated string containing values of <code>tag_name</code> key like so. </p>
  
  <pre><code>google, technology
  </code></pre>
  
  <p>Is it possible to achieve this effect with the said function? If not then please suggest an alternate solution.</p>