mysql Update problem

<?php
$cfid = '{cf_id}';
 $sql = "UPDATE `cdcserver`.`jos_chronoforms_anagrafic` SET `file_identita` = '' WHERE `jos_chronoforms_anagrafic`.`cf_id` = ".$cfid.";
 "; 
 mysql_query($sql) or die(mysql_error()); 
 echo $cfid;
  ?>

This is my problem, if I change '{cf_id}' with a number the Update works, if I remove the mysql_query($sql)part the echo stamp the correct number but if I try both of them then something wrong happens "You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '}' at line 1"
Hope you can help me, thanks.