To sort with varying strings:
2
3a
3b
4
10
Use below query:
ORDER BY CAST(mini_number AS UNSIGNED), mini_number
References:
https://www.sitepoint.com/community/t/mysql-how-to-sort-numbers-with-some-data-also-containing-a-letter/340999
https://www.sitepoint.com/community/t/how-to-sort-text-with-numbers-with-sql/346088/4