WordPress Version: 3.7
/**
* Move child posts to a new parent.
*
* @since 2.3.0
* @access private
*
* @param unknown_type $old_ID
* @param unknown_type $new_ID
* @return unknown
*/
function _relocate_children($old_ID, $new_ID)
{
global $wpdb;
$old_ID = (int) $old_ID;
$new_ID = (int) $new_ID;
$children = $wpdb->get_col($wpdb->prepare("\n\t\tSELECT post_id\n\t\tFROM {$wpdb->postmeta}\n\t\tWHERE meta_key = '_wp_attachment_temp_parent'\n\t\tAND meta_value = %d", $old_ID));
foreach ($children as $child_id) {
$wpdb->update($wpdb->posts, array('post_parent' => $new_ID), array('ID' => $child_id));
delete_post_meta($child_id, '_wp_attachment_temp_parent');
}
}