MySQL实现分组排序并取组内第一条数据

错误示范：

select t.* from (
    select * from error_record e order by e.begin_time desc
) t group by t.error_type

正确示范：

内部子查询用limit字段，可固定排序

select t.* from (
    select * from error_record e order by e.begin_time desc limit 1000
) t group by t.error_type