How to Combine GROUP CONCAT with COUNT in MySQL?

If I understand correctly, this is just join but with two levels of aggregation:

select its.*, ic.categories
from item_sale its join
     (select isd.isd_sale_id,
             group_concat(ic_name, ':', cnt order by cnt desc) as categories
      from (select isd.isd_sale_id, ic.ic_name, count(*) as cnt
            from item_sale_detail isd join
                 items i
                 on isd.isd_item = i.i_id join
                 item_category ic
                 on i.i_category = ic.ic_id
            group by isd.isd_sale_id, ic.ic_name
           ) ic
      group by isd.isd_sale_id
     ) ic
     on i.is_id = ic.isd_sale_id;