题解 | 商品销售总额分布

/*注意：脏数据包括空值和空字符串，二者概念不同，虽然题目未要求处理空值，但还是加上会严谨一些，空字符串要用单引号，聚合函数和group by 优先用group by,因为窗口函数可能会有重复计算，group by 直接去重了，更加简洁明了。
初--步--框--架
联表：
from user_client_log u
join product_info p on u.product_id = p.product_id
计数；count(*) over(partition by pay_method) as cnt
排序：order by cnt desc
筛选：where pay_method != "'" and pay_method is not null
*/
select 
case 
    when pay_method = '' or pay_method is null then "error" 
    else pay_method 
    end
as pay_method
,count(step) as cnt
from user_client_log u
join product_info p on u.product_id = p.product_id
where product_name = "anta"
and step = "select"
group by case 
    when pay_method = '' or pay_method is null then "error" 
    else pay_method 
    end
order by cnt desc