quickest solution
select sell_date, \ncount(distinct product) as num_sold, \ngroup_concat(distinct product) as products\nfrom Activities\ngroup by sell_date\norder by sell_date,p
select sell_date, \ncount(distinct product) as num_sold, \ngroup_concat(distinct product) as products\nfrom Activities\ngroup by sell_date\norder by sell_date,products
['MySQL']