title: mysql_real_escape_string is undefined
body: <p>I am using PHP version 5.3 and trying to use <code>mysql_real_escape_string($unescaped_string)</code> in my code, but I get the error:</p>
  
  <pre><code>Fatal error: Call to undefined function mysql_real_escape_string() 
  in /var/www/engine/database.php on line 38
  </code></pre>
  
  <p>I can still connect to the database however.  Why is it not available?</p>
  
  <p>I am using PHP version 5.3.</p>