获取每个帐号最后更新时间

订单表里，o_account为帐号,o_load_time为导单时间 SELECT o_load_time, `o_account` FROM `v2_order` GROUP BY o_account order by o_load_time desc 我用如上sql获取的o_load_time不是最大值
40分	SELECT max(o_load_time), `o_account` FROM `v2_order` GROUP BY o_account