Assigning Value to PHP 'set'

I'm saving a new file with several fields. One field needs to have the save value as the new file itself (ex. if the file saved will be #100 the field also needs to be #100) see in bold below:

mysql_query("INSERT INTO `{$TABLE_PREFIX}member_companies` SET

member_company_name           = '".mysql_escape( $_REQUEST['member_company_name'] )."',              
member_type                             = '".mysql_escape( $_REQUEST['member_type'] )."',
contact_name                             = '".mysql_escape( $_REQUEST['contact_name'] )."',

assigned                                   = '".mysql_escape( $_REQUEST['?????'] )."',

receive_urls                               = '1'")

     or die("MySQL Error Creating Member Company Record:<br/>\n". htmlspecialchars(mysql_error()) . "\n");

Any help would be appreciated!

Thanks

NMSINC