mysql计数然后按该计数分组

Question

I have a table structured like this:

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

What I would like to do is first count how many saved ids each user has, and then group these results so that I know how often each total_saves occurs.

This is what I currently have:

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

Which gives me

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

What I would like to have is this:

total_saves   count
3             2
2             1
1             3

Can't get my head around how to group the total_saves that I already have. I tried GROUP BY total_saves but that doesn't work.

Answer 1

Use two aggregations:

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

Use Subquery

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;