title: Codeigniter Illegal string offset server issue in PostgreSQL query
body: <p>we are using PostGreSql database, when we run following code unit, it shows error of.</p>
  
  <pre><code> Severity: Warning
   Message: Illegal string offset 'server'
   Filename: postgre/postgre_driver.php
  
  
  Message: Cannot modify header information - headers already sent by (output started at       system/core/Exceptions.php:185)
  </code></pre>
  
  <p><strong>Model Code:</strong></p>
  
  <pre><code>public function tracks_add( $id ) {
      $cnt = 0;
      $date = date('Y-m-d H:i:s');
  
      $s_title = $this-&gt;input-&gt;post('s_title');
      $s_singer = $this-&gt;input-&gt;post('s_singer');
      $s_url = $this-&gt;input-&gt;post('s_url');
  
      foreach ($s_title as $s_title) {
          $this-&gt;db-&gt;set( array('a_id'=&gt; $id, 's_title' =&gt; $s_title, 's_singer' =&gt; $s_singer[$cnt], 's_url' =&gt; $s_url[$cnt], 'date'=&gt; $date) );
          $this-&gt;db-&gt;insert('soundtracks');
  
          $cnt++;
      }
  }
  </code></pre>