selectcoalesce(tran_cou,0) as tran_cou,sum(vis_cou) as vis_coufrom(select user_id, visit_date,count(*) as vis_cou from leetcode.ex_1336_visits group by user_id,visit_date) a left join(select user_id,transaction_date,count(*) as tran_cou from leetcode.ex_1336_transactions group by user_id,transaction_date )bon a.user_id=b.user_id and a.visit_date=b.transaction_dateGROUP BYcoalesce(tran_cou,0);