mysql查询最大重复值

Question

 b_id | s_id | doi        | dos        | charge |
+------+------+------------+------------+--------+
|   10 |    3 | 0000-00-00 | 0000-00-00 |    200 |
|   10 |    2 | 0000-00-00 | 0000-00-00 |    200 |
|   20 |    1 | 0000-00-00 | 0000-00-00 |    200 |
|   30 |    2 | 0000-00-00 | 0000-00-00 |    200 |
|   40 |    4 | 0000-00-00 | 0000-00-00 |    200 |
|   40 |    5 | 0000-00-00 | 0000-00-00 |    200 |
|   70 |    5 | 0000-00-00 | 0000-00-00 |    200 |
|   40 |    4 | 0000-00-00 | 0000-00-00 |    200 |

mysql查询找到重复最长时间的b_id？我试过了

select count(*) as counted from(select b_id from books) group by b_id

但它不会只返回40 ...有什么方法我可以从查询中得到40

Answer 1

select b_id, count(b_id) 
from books 
group by b_id 
order by count(b_id) desc
limit 1;