I would write a new wp plug-in
I have two files named a.php and b.php
a.php is the core that i have registered in wordpress plug-in page ,and every things work fine.
in a.php, i need open b.php in a new window, and i also need require admin.php to call the $wpdb function.
It error on
require_once(ABSPATH . '/wp-admin/includes/admin.php');
After i echo the ABSPATH , it is blank.
Should need to call any function to preserve the global variable?