I have errors in my php file:
Warning: require_once(DIR/db_connect.php) [function.require-once]: failed to open stream: No such file or directory in /home/a6869653/public_html/get_product_details.php on line 11
but I have uploaded the db_connect.php in the same directory as the others.
require_once __DIR__ . DS . 'db_connect.php';
or
require_once __DIR__ . '/db_connect.php';
should do.
Try to remove the DIR and replace it with require