PHP / MYSQL Distinct运算符，具有多个字段和字段选择

Question

我有一个MYSQL表，看起来像： +----+--------------+------------+----------------+---------------------+ | id | id_solicitud | id_estatus | id_responsable | fecha_hora | +----+--------------+------------+----------------+---------------------+ | 1 | 1 | 1 | 3 | 2017-11-20 11:12:05 | | 3 | 1 | 2 | 3 | 2017-11-20 13:30:50 | | 4 | 2 | 1 | 5 | 2017-11-20 13:42:35 | | 5 | 2 | 2 | 5 | 2017-11-20 13:52:25 | | 6 | 1 | 4 | 2 | 2017-11-21 12:20:17 | | 8 | 2 | 3 | 2 | 2017-11-21 13:39:57 | | 9 | 2 | 2 | 5 | 2017-11-21 13:40:55 | | 10 | 2 | 4 | 2 | 2017-11-21 13:45:24 | +----+--------------+------------+----------------+---------------------+

然后，我继续使用以下Mysql QUERY过滤 id_solicitud 字段：

SELECT id_estatus，id_responsable，fecha_hora FROM estatus_historico WHERE id_solicitud = 2 ORDER BY fecha_hora

结果： +------------+----------------+---------------------+ | id_estatus | id_responsable | fecha_hora | +------------+----------------+---------------------+ | 1 | 5 | 2017-11-20 13:42:35 | | 2 | 5 | 2017-11-20 13:52:25 | | 3 | 2 | 2017-11-21 13:39:57 | | 2 | 5 | 2017-11-21 13:40:55 | | 4 | 2 | 2017-11-21 13:45:24 | +------------+----------------+---------------------+

我想在 id_estatus 列上应用distinct运算符，但在找到重复行时选择较旧的行，即我想要的结果是： +------------+----------------+---------------------+ | id_estatus | id_responsable | fecha_hora | +------------+----------------+---------------------+ | 1 | 5 | 2017-11-20 13:42:35 | | 3 | 2 | 2017-11-21 13:39:57 | | 2 | 5 | 2017-11-21 13:40:55 | | 4 | 2 | 2017-11-21 13:45:24 | +------------+----------------+---------------------+

我试过了：

SELECT id_estatus，id_responsable，fecha_hora FROM estatus_historico WHERE id_solicitud = 2 GROUP BY id_estatus ORDER BY fecha_hora

但结果是错误的： +------------+----------------+---------------------+ | id_estatus | id_responsable | fecha_hora | +------------+----------------+---------------------+ | 1 | 5 | 2017-11-20 13:42:35 | | 2 | 5 | 2017-11-20 13:52:25 | | 3 | 2 | 2017-11-21 13:39:57 | | 4 | 2 | 2017-11-21 13:45:24 | +------------+----------------+---------------------+

非常感谢任何帮助

更新：要创建表格和插入数据的文件=＆gt; estatus_historico.sql

Answer 1

尝试这个

SELECT id_estatus, id_responsable, MAX(fecha_hora) FROM estatus_historico WHERE id_solicitud =2 GROUP BY id_estatus ORDER BY fecha_hora

Answer 2

感谢Rahul Shrivastava，我终于找到了正确答案：

SELECT * FROM ( SELECT id_estatus, id_responsable, MAX( fecha_hora ) AS fecha FROM estatus_historico WHERE id_solicitud =2 GROUP BY id_estatus ORDER BY fecha_hora ) AS MY_TABLE ORDER BY fecha