MySQL Sorting by turns

问题

I want to sort the following data items in the order they are presented below :

id | res
--------
1     A
2     A
3     A
4     A
5     A
6     B
7     B
8     B
9     B
10    B
11    C
12    C
13    C
14    C
15    C

And i want the output is :

res
---
A
B
C
A
B
C
A
B
C
A
B
C
A
B
C

Any tricks to make it sort more properly?

Many Thanks!

回答1:

You can order by the "rank" within the group. The rank can be calculated using a self join and counting the entries with lesser ids.

select t1.id, t1.res
from mytable t1
join mytable t2
  on  t2.res = t1.res
  and t2.id <= t1.id
group by t1.id, t1.res
order by count(*), t1.res

http://rextester.com/ICHZNN18920

来源：https://stackoverflow.com/questions/40060102/mysql-sorting-by-turns