title: Showing comma separated dropdown values from column in database
body: <p>I have saved multiple choices from dropdown select menu into database field and separate them with comma. How can I load now them in dropdown menu again?
  They are saved as: <code>choice1</code>,<code>choice2</code>,<code>choice55</code>...etc. Currently my query joining two tables and it's look's like this:</p>
  
  <pre><code>$pdo = Database::connect();
  $sql="SELECT t1.*, t2.*
      FROM form_fields t1, user_choices t2
      WHERE t1.field_name = t2.field_name
      and group_id=1 and user_id=".$_SESSION['user_id']." 
  
      echo '&lt;select class="form-control" name="program"&gt;';
      foreach ($pdo-&gt;query($sql) as $row_program){
              echo '&lt;option value='.$row_program['field_name'].'&gt;'.$row_program['field_name'].'&lt;/option&gt;'; 
      }
  echo '&lt;/select&gt;';
  </code></pre>
  
  <p>So I need to display values from <code>user_choices t2</code> column <code>program</code>. This query showing result if there is only one value in the column. But when there is multiple value saved with comma showing error</p>
  
  <pre><code>PHP Warning:  Invalid argument supplied for foreach()...
  </code></pre>