需要帮助将列分组为年份和月份

Question

有人可以告诉我为什么我在“年度明智”中获得总数“客户”的不同金额，即第一次查询和“月份明智”，即第二次查询。

select year(order_date), year(first_order_date),
count(distinct customer_mobile) as 'Customers',
count(customer_mobile) as 'Orders',
sum(order_amount)
from order_table
group by year(order_date),year(first_order_date)

vs

select year(order_date), month(order_date), year(first_order_date),
count(distinct customer_mobile) as 'Customers',
count(customer_mobile) as 'Orders',
sum(order_amount)
from order_table
group by year(order_date),month(order_date),year(first_order_date)

由于

Answer 1

不同的总和，因为在第一个查询中，您已按两年分组

所以总和将是多年。

在第二个查询中，您按月添加了所有结果将按月添加，按年份和月份不同。

例如

    user1 ---> 40 per year /if you group by year

和

   user1---> 10 january , 10 favruary , 5 mars ,... ///---if you group by month.

Answer 2

在第一个查询中，如果客户在一年内有多个订单，则只计算一次。在第二个查询中，客户每年/每月组合计算一次。

您可以尝试第二次查询：

select CONCAT(year(order_date), '-', month(order_date)) as yearmonth,
year(first_order_date),
count(distinct customer_mobile) as 'Customers',
count(customer_mobile) as 'Orders',
sum(order_amount)
from order_table
group by CONCAT(year(order_date), '-', month(order_date)),year(first_order_date)