title: PHP isset() with multiple parameters
body: <p>I'm trying to work with AJAX autocompletes and I am having a few problems with getting the two languages to work in synergy.</p>
  
  <p>When I replace all the issets with only 1 $_POST the snippet below will work, however by adding another $_POST I get an error on line 5.</p>
  
  <pre><code>&lt;?php 
  
  require_once '../Configuration.php';
  if (isset($_POST['search_term'] . $_POST['postcode']) == true &amp;&amp; empty ($_POST['search_term'] . $_POST['postcode']) == false) {
  $search_term = mysql_real_escape_string($_POST['search_term'] . $_POST['postcode']);
  $query = mysql_query("SELECT `customer_name`,`postcode` FROM `Customers` WHERE `customer_name` LIKE '$search_term%' ");
  while(($row = mysql_fetch_assoc($query)) !== false) {
      //loop
      echo '&lt;li&gt;',$row['customer_name'] . $row['postcode'] '&lt;/li&gt;';
  }
  }
  
  
  ?&gt;
  </code></pre>
  
  <p>Any advice on why it is throwing this error would be much appreciated. Thanks.</p>
  
  <p>I understand I should be using mysqli, I am just trying to get the logic first :)</p>
  
  <p>Js:</p>
  
  <p>Primary.js:</p>
  
  <pre><code>$(document).ready(function() {
  $('.autosuggest').keyup(function() {
  
      var search_term = $(this).attr('value');
      var postcode = $_GET['postcode'];
      //alert(search_term); takes what is typed in the input and alerts it
      $.post('ajax/search.php', {search_term:search_term, postcode:postcode},     function (data) {
          $('.result').html(data);
          $('.result li').click(function() {
              var result_value = $(this).text();
              $('.autosuggest').attr('value', result_value);
              $('.result').html('');
  
          });
      });
  });
  });
  </code></pre>