Question

我正在尝试获得如下所示的结果，列名无关紧要，以后我可以对其进行编辑。

Date - Visit Amount- Customer Count by Visit Amount 
2020        1                  10                   
2020        2                  50                   
2020        3                  123                  
2020        6                  24

我有date和customer_id列。简而言之，我试图确定在2020年有1次，2次等访问过我的商店的顾客有多少。我找不到，因为访问量无法分组。

Answer 1

我试图在2020年发现有1次，2次等的顾客来过我的商店。

您可以使用两种聚合级别：

select num_visits, count(*) as num_customers
from (select customer_id, count(*) as num_visits
      from visits v
      where visit_dt >= '2020-01-01' and visit_dt < '2021-01-01'
      group by customer_id
     ) v
group by num_visits
order by num_visits;

这构成了表名和列名，因为您的问题未提供它们。但是应该很容易看到它在做什么。

编辑：

如果要分别每年：

select year, num_visits, count(*) as num_customers
from (select year(visit_dt) as year, customer_id, count(*) as num_visits
      from visits v
      group by year(visit_dt), customer_id
     ) v
group by year, num_visits
order by year, num_visits desc;

Answer 2

您可以使用CTE。

WITH TBL AS (
    --your first grouping query here
),
AS TBL2 (
    SELECT 
        COUNT(Visit_Amount) Visit_Amount,
        COUNT(Customer_Count_by_Visit_Amount) Customer_Count_by_Visit_Amount
    FROM TBL 
    GROUP BY Visit_Amount,Customer_Count_by_Visit_Amount
)
SELECT * FROM TBL2

如何计算和按同一列分组

2 个答案: