Oracle SQL组由单个字段组成，并计算分组的行数

Question

考虑此表some_table：

+--------+----------+---------------------+-------+
| id     | other_id | date_value          | value |
+--------+----------+---------------------+-------+
| 1      | 1        | 2011-04-20 21:03:05 | 104   |
| 2      | 1        | 2011-04-20 21:03:04 | 229   |
| 3      | 3        | 2011-04-20 21:03:03 | 130   |
| 4      | 1        | 2011-04-20 21:02:09 | 97    |
| 5      | 2        | 2011-04-20 21:02:08 | 65    |
| 6      | 3        | 2011-04-20 21:02:07 | 101   |
| ...    | ...      | ...                 | ...   |
+--------+----------+---------------------+-------+

我想按other_id选择和分组，这样我才能获得唯一的other_id。此查询有效（信用@MichaelPakhantsov）：

select id, other_id, date_value, value from
 (
   SELECT id, other_id, date_value, value, 
   ROW_NUMBER() OVER (partition by other_id order BY Date_Value desc) r
   FROM some_table 
 )
 where r = 1

如何为每个other_id获得相同的结果，但计算分组的行数。期望的结果如下：

+--------+----------+---------------------+-------+-------+
| id     | other_id | date_value          | value | count |
+--------+----------+---------------------+-------+-------+
| 1      | 1        | 2011-04-20 21:03:05 | 104   | 3     |
| 5      | 2        | 2011-04-20 21:02:08 | 65    | 2     |
| 3      | 3        | 2011-04-20 21:03:03 | 130   | 2     |
+--------+----------+---------------------+-------+-------+

我已尝试在内部和外部选择中使用COUNT(other_id)，但会产生此错误：

  

ORA-00937：不是单组组功能

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注意：类似于this question（示例表和从中获取的答案），但该问题没有给出折叠行的计数。

Answer 1

添加

count(*) OVER (partition by other_id) cnt

到内部查询

select id, other_id, date_value, value, cnt from
 (
   SELECT id, other_id, date_value, value, 
   ROW_NUMBER() OVER (partition by other_id order BY Date_Value desc) r,
   count(*) OVER (partition by other_id) cnt
   FROM some_table 
 )
 where r = 1