select user_id,max(counts) as days_count
from (
  select user_id,d,count(*) as counts
	from (
    	select user_id,date_sub(sales_date,interval rk day) as d
    	from (
        	select *,
            	row_number () over(partition by user_id order by sales_date) as rk
        	from sales_tb
        	) as rk
    	) as d
	group by user_id,d
	) as c
group by user_id
having max(counts)>=2
order by user_id