thinkphp（tp5）分组并取分组内最新

$subQuery  = $db2->table("app_register_info")
            ->where('update_time','>=','2018-06-20 23:59:59')
            ->order('update_time desc')
            ->buildSql();
$data = $db2->table($subQuery."a")
            ->field("a.loginTel u_phone,concat('用户',a.loginTel) u_name,a.loginPWD u_pass,a.update_time u_time")
            ->group('loginTel')
            ->order('update_time desc')
            ->select();