Multiple database connection not working with new_link=TRUE and sql.safe_mode = OFF

Question

I'm tryng to connect a different database from a php function (assuming there's a current connection to another database). I'm using mysql_connect() with new_link parameter set to TRUE as you can see below. How is it possible the following code returns global_thread_id=16357138 local_thread_id=16357139 current_global=16357139 (meaning local connection overriden previous connection) despite the TRUE in mysql_connect()

Also in php settings, sql.safe_mode = OFF

// Class static method
static function Query($sql) {
       $global_thread_id = mysql_thread_id();
       if ($link = mysql_connect(FB_DB_HOST, FB_DB_USER, FB_DB_PASS, true)) 
       {
            $local_thread_id = mysql_thread_id($link);                          
            echo 'global_thread_id='.$global_thread_id.' local_thread_id='.$local_thread_id.' current_global='.mysql_thread_id();   
       }
}

Answer 1

mysql_thread_id() fetch the latest thread id, not a "global"

php manual for mysql_thread_id says:

Retrieves the current thread ID

// Class static method
static function Query($sql) {

       /* fetch latest thread id = global */
       $global_thread_id = mysql_thread_id();
       if ($link = mysql_connect(FB_DB_HOST, FB_DB_USER, FB_DB_PASS, true)) 
       {
            /* fetch thread id from $link */
            $local_thread_id = mysql_thread_id($link);

            /* echo 2 vars and the latest thread id = same as link */
            echo 'global_thread_id='.$global_thread_id.' local_thread_id='.$local_thread_id.' current_global='.mysql_thread_id();   
       }
}