如何按列对组内元素进行排序？

Question

尝试订购：

|    id    |    title    |    created_at    |

 1                            12:00  
 2                            13:00
 1                            15:00
 2                            15:00
 1                            17:00
 3                            18:00
 1                            19:00
 3                            20:00

进入这个：

3    20:00
3    18:00
1    19:00
1    17:00
1    15:00
1    12:00
2    15:00
2    13:00

这种代码的和平完成了工作分组ID：

select t.*
from table t join
     (select t.id, max(created_at) as maxca
      from table t
      group by t.id
     ) tt
     on t.id = tt.id
order by tt.maxca desc, id;

问题是created_at以相反的顺序出现，如下所示：

3    18:00
3    20:00
1    12:00
1    15:00
1    18:00
1    19:00
2    13:00
2    15:00

如何在每个分组的id块中反转created_at顺序？

Answer 1

select * from table order by id desc,created_at desc

Answer 2

只需向order by添加另一个密钥：

select t.*
from table t join
     (select t.id, max(created_at) as maxca
      from table t
      group by t.id
     ) tt
     on t.id = tt.id
order by tt.maxca desc, id, created_at desc;

Answer 3

所以你必须删除 tt.maxca 并在你的分组中添加 created_at ：

select t.*
from table t join
     (select t.id, max(created_at) as maxca
      from table t
      group by t.id
     ) tt
     on t.id = tt.id
order by id desc, created_at desc;