Orden fecha usuarios en sección

function modify_user_columns($column) {
$column = array(
"cb" => "",
"fecha" => "fecha",//the new column
"username" => "Username",
"email" => "E-mail",
"role" => "Role"
);
return $column;
}
add_filter('manage_users_columns','modify_user_columns');

//add content to your new custom column
function modify_user_column_content($val,$column_name,$user_id) {
$user = get_userdata($user_id);
switch ($column_name) {
case 'fecha':
return $user->fecha;
break;
//I have additional custom columns, hence the switch. But am only showing one here
default:
}
return $return;
}
add_filter('manage_users_custom_column','modify_user_column_content',10,3);

//make the new column sortable
function user_sortable_columns( $columns ) {
$columns['fecha'] = 'fecha';
return $columns;
}
add_filter( 'manage_users_sortable_columns', 'user_sortable_columns' );

//set instructions on how to sort the new column
if(is_admin()) {//prolly not necessary, but I do want to be sure this only runs within the admin
add_action('pre_user_query', 'my_user_query');
}

function my_user_query($userquery){
if('fecha'==$userquery->query_vars['orderby']) {//check if church is the column being sorted
global $wpdb;
$userquery->query_from .= " LEFT OUTER JOIN $wpdb->usermeta AS alias ON ($wpdb->users.ID = alias.user_id) ";//note use of alias
$userquery->query_where .= " AND alias.meta_key = 'fecha' ";//which meta are we sorting with?
$userquery->query_orderby = " ORDER BY alias.meta_value ".($userquery->query_vars["order"] == "ASC" ? "asc " : "desc ");//set sort order

}
}