尝试计算总订单和每月唯一客户

Question

我想获得30天内的订单总量和独立客户数量。

我有这个表:

order_id, order_date, order_country, customer_id.

(1, '2021/03/04', 'SWE', 1),
(2, '2021/03/01', 'SWE', 1),
(3, '2021/03/01', 'DK', 3),
(4, '2021/03/01', 'DK', 3),
(5, '2021/03/03', 'NOR', 2),
(6, '2021/02/27', 'DK', 3),
(7, '2020/12/30', 'Ger', 4);

我试过这样做:

SELECT order_date
, COUNT(order_id) as orderAmount
, COUNT(distinct customer_id) as customerAmount 
FROM orders
WHERE order_date BETWEEN NOW() - INTERVAL 30 DAY AND NOW() 
GROUP 
BY order_date

获取每个日期的订单总数，这是我想要的。但它只计算每个日期的唯一客户，而不是每月的，所以同一个客户会出现多次。我已经尝试了这个sql脚本的小变化，但不能完全得到它的工作。

Answer 1

请检查一下这是不是你想要的答案

Schema (MySQL v5.5)

create table orders (order_id int, order_date date, order_country varchar(10), customer_id int);
insert into orders values(1, '2021/03/04', 'SWE', 1);
insert into orders values(2, '2021/03/01', 'SWE', 1);
insert into orders values(3, '2021/03/01', 'DK', 3);
insert into orders values(4, '2021/03/01', 'DK', 3);
insert into orders values(5, '2021/03/03', 'NOR', 2);
insert into orders values(6, '2021/02/27', 'DK', 3);
insert into orders values(7, '2020/12/30', 'Ger', 4);

---

查询# 1

SELECT 
o.order_date,COUNT(order_id) as orderAmount
, coalesce(max(Customer_Count),0) as customerAmount 
FROM orders o left join (select order_date,count(distinct customer_id)Customer_Count from orders o where 
not exists (select customer_id from orders oa where o.customer_id=oa.customer_id and oa.order_date<o.order_date
and oa.order_date > now() - INTERVAL 30 DAY  )
group by order_date) oc on o.order_date=oc.order_date
WHERE o.order_date BETWEEN NOW() - INTERVAL 30 DAY AND NOW() 
group by o.order_date
order by o.order_date;

tbody> <<tr>

order_date	orderAmount	customerAmount
2021-02-27	1	1
2021-03-01	3	1
2021-03-03	1	1
2021-03-04	1	0

计算顾客第一次出现的次数:

SELECT order_date, COUNT(*) as num_orders,
COUNT(DISTINCT customer_id) as distinct_customers_on_day,
SUM(SUM(seqnum = 1)) OVER (ORDER BY order_date) as running_distinct_customers
FROM (SELECT o.*, 
ROW_NUMBER() OVER (PARTITION BY customer_id ORDER BY order_date) as seqnum
FROM orders o
WHERE o.order_date BETWEEN NOW() - INTERVAL 30 DAY AND NOW() 
) o
GROUP BY order_date;

这是一个db<>小提琴