对于mysql 5.5版本
select * from ( select * from table_name order by create_time desc) as a group by a.id;对于mysql 5.7及以上版本,需要加入limit限制，否则不生效
SELECT * FROM ( SELECT * FROM `zyy_plant` ORDER BY `id` DESC LIMIT 100000000 )a GROUP BY `create_time`TP5
//子查询
$sql = Plant::order('id desc')->limit(100000000)->buildSql();
$_data = Plant::table($sql.'a')->field(array_values($field_arr))->group('create_time')->select();