set_lastupdated_to_lastpostdate.php
<?php
function set_lastupdated_to_lastpostdate( $wpdb_blogid ) {
switch_to_blog( $wpdb_blogid );
$lastpostdate = get_lastpostdate( 'blog' );
// Update the last_updated time
update_blog_details( $wpdb_blogid, array('last_updated' => $lastpostdate ) );
echo 'Last Post Date for site ' . $wpdb_blogid . ' Updated to: ' . $lastpostdate . '<br>';
echo 'Last Updated Date for site ' . $wpdb_blogid . ' is currently: ' . get_blog_details( $blogId )->last_updated;
restore_current_blog();
}
# Debug bar test
set_lastupdated_to_lastpostdate( '11' );