mysql計數然后按該計數分組

Question

我有一個像這樣結構的表：

user_id   saved_id
1         2
1         34
1         36
2         489
2         14
3         731
4         48
5         901
6         234
6         9
6         64

我想要做的是首先計算每個用戶有多少已保存的ID，然后將這些結果分組，以便我知道每個total_saves發生的頻率。

這就是我目前擁有的：

SELECT user_id, count(*) as total_saves FROM table GROUP BY user_id ORDER BY total_saves DESC

哪能給我

user_id   total_saves
1         3
6         3
2         2
3         1
4         1
5         1

我想擁有的是：

total_saves   count
3             2
2             1
1             3

無法理解如何對我已經擁有的total_saves進行分組。 我嘗試了GROUP BY total_saves但這不起作用。

Answer 1

使用兩個聚合：

select total_saves, count(*) as cnt
from (select user_id, count(*) as total_saves
      from t
      group by user_id
     ) t
group by total_saves;

Answer 2

使用子查詢

select total_saves, count(total_saves) as count
from (select user_id, count(*) as total_saves
  from table
  group by user_id
 ) a
group by total_saves order by total_saves;