mysql_thread_id
    (PHP 4 >= 4.3.0, PHP 5)
mysql_thread_id -- Return the current thread ID
Description
int 
mysql_thread_id ( [resource link_identifier] )
   Retrieves the current thread ID. If the connection is lost, and a reconnect 
   with mysql_ping() is executed, the thread ID will 
   change. This means only retrieve the thread ID when needed.
  
Parameters
   
- 
link_identifier
 The MySQL connection. If the 
link identifier is not specified, the last link opened by 
mysql_connect() is assumed. If no such link is found, it
will try to create one as if mysql_connect() was called
with no arguments. If by chance no connection is found or established, an
E_WARNING level warning is generated.
 
  Return Values
   The thread ID on success, or FALSE on failure.
  
Examples
   
Example 1. mysql_thread_id() example 
<?php $link = mysql_connect('localhost', 'mysql_user', 'mysql_password'); $thread_id = mysql_thread_id($link); if ($thread_id){     printf("current thread id is %d\n", $thread_id); } ?>
 |  
 The above example will output 
something similar to:  |