title: "SELECT * FROM users WHERE id IN ( )" == FAIL
body: <p>I have a function that I use called sqlf(), it emulates prepared statements.  For instance I can do things like:</p>
  
  <pre>
  $sql = sqlf("SELECT * FROM Users WHERE name= :1 AND email= :2",'Big "John"','bj@example.com') ;
  </pre>
  
  <p>For various reasons, I cannot use prepared statements, but I would like to emulate them.  The problem that I run into is with queries like</p>
  
  <pre>
  $sql = sqlf("SELECT * FROM Users WHERE id IN (:1)",array(1,2,3) );
  </pre>
  
  <p>My code works, but it fails with empty arrays, e.g. the following throws a mysql error:</p>
  
  <pre>
  SELECT * FROM Users WHERE id IN ();
  </pre>
  
  <p>Does anyone have any suggestions?  How should I translate and empty array into sql that can be injected into an IN clause?  Substituting NULL will not work.  </p>