Question

我有一个SQL表，该表包含三列：customer_id，他们的第一笔订单的日期和他们的最后一张订单的日期。我正在尝试创建一个报告，以显示过去30天内重新订购的现有客户的百分比...即如果客户的第一笔订单在30天之前，而最后一笔订单在最近30天之内，则他们将计算在分子中。如果客户的第一笔订单在30天之前，那么他们将计入分母。

我希望输出只有两列：1）日期按时间顺序逆转； 2）符合该日期以上条件的客户百分比。我似乎无法弄清楚如何生成此报告。

有人知道如何开始吗？

Answer 1

您可以为此使用lag()。

select avg(case when last_order_date >= dateadd(day, -30, current_date) then 1.0 else 0 end)
from t
where first_order_date < dateadd(day, -30, current_date);

Answer 2

很酷，所以它是一个“从一个地方获取两个结果，然后合并结果”的查询吗？如果您可以保证一个具有唯一的customer_id的客户表，这应该可以工作。我认为一天中总计的百分比方法比分子/分母更好，因为不会有“新”客户为0的日子和“老”客户为零的日子吗？

我也不太清楚，更重要的是新客户还是旧客户？这样可以提供一定比例的新客户，您可以根据需要切换显示旧客户的比例。

------- just some fake data - you won't need this because you have the real thing
WITH  CUSTOMER_TABLE AS     (

SELECT   1  AS customer_id  ,   CAST('2017-08-01' AS  DATE) AS first_order_date  ,  CAST('2018-07-05' AS DATE)  AS  last_order_date   UNION
SELECT   2   ,  '2018-07-01'   , '2018-07-06'    UNION
SELECT   3   ,  '2018-07-01'   , '2018-07-07'    UNION
SELECT   4   ,  '2018-07-01'   , '2018-07-08'    UNION
SELECT   5   ,  '2018-06-01'   , '2018-07-09'    UNION
SELECT   6   ,  '2018-05-31'   , '2018-07-10'    UNION
SELECT   7   ,  '2018-07-01'   , '2018-07-11'    UNION
SELECT   8   ,  '2018-07-01'   , '2018-07-12'    UNION
SELECT   9   ,  '2018-07-01'   , '2018-07-13'    UNION
SELECT   10  ,  '2018-07-01'   , '2018-07-14'    UNION
SELECT   11  ,  '2018-07-01'   , '2018-07-15'    UNION
SELECT   12  ,  '2018-03-04'   , '2018-07-16'    UNION
SELECT   13  ,  '2018-01-01'   , '2018-07-17'    UNION
SELECT   14  ,  '2018-07-01'   , '2018-07-17'    UNION
SELECT   15  ,  '2018-07-01'   , '2018-07-17'    UNION
SELECT   16  ,  '2018-01-01'   , '2018-07-18'    UNION
SELECT   17  ,  '2018-02-01'   , '2018-07-18'    UNION
SELECT   18  ,  '2018-07-02'   , '2018-07-18'    UNION
SELECT   19  ,  '2018-07-01'   , '2018-07-18'    

)


SELECT   last_order_date  ,  
------ note the "1.00" forcing PostgreSQL to return a decimal result
1.00 * (count_of_new_customers)/(count_of_old_customers + count_of_new_customers ) AS percentage_of_new_customers , 
count_of_old_customers  ,   count_of_new_customers    ,
count_of_old_customers + count_of_new_customers AS total_customers_for_the_day   

FROM

(
SELECT last_order_date   ,
CAST(COUNT (CASE WHEN DATEDIFF(DAY,   first_order_date , last_order_date)  > 30 THEN 'old customer'  END  ) AS integer)   AS  count_of_old_customers  ,
CAST(COUNT (CASE WHEN DATEDIFF(DAY,   first_order_date , last_order_date)  <= 30 THEN 'new customer'  END ) AS integer)   AS  count_of_new_customers 
----replace  CUSTOMER_TABLE with your actual schema.table
FROM        CUSTOMER_TABLE
GROUP BY  last_order_date 
)

-----  here is the descending last_order_date you wanted
ORDER BY   last_order_date    DESC

过去30天的总结和案例逻辑

2 个答案: