是否有 SQL 代碼用於幾個月內 SaaS 客戶的累積計數？

Question

我有一個表：ID（id 客戶端）、date_start（SaaS 訂閱）、date_end（可以是日期值或為 NULL）。

所以我需要逐月累積活躍客戶的數量。

關於如何在 Postgres 中編寫並實現此結果的任何想法？

從這里開始，但我不知道如何進行

select 
date_trunc('month', c.date_start)::date,
count(*) 
from customer

Answer 1

請檢查下一個解決方案：

select 
    subscrubed_date,
    subscrubed_customers,
    unsubscrubed_customers,
    coalesce(subscrubed_customers, 0) - coalesce(unsubscrubed_customers, 0) cumulative
from (
    select distinct
    date_trunc('month', c.date_start)::date subscrubed_date,
    sum(1) over (order by date_trunc('month', c.date_start)) subscrubed_customers
    from customer c
    order by subscrubed_date
) subscribed
left join (
    select distinct
    date_trunc('month', c.date_end)::date unsubscrubed_date,
    sum(1) over (order by date_trunc('month', c.date_end)) unsubscrubed_customers
    from customer c
    where date_end is not null
    order by unsubscrubed_date
) unsubscribed on subscribed.subscrubed_date = unsubscribed.unsubscrubed_date;

分享SQL查詢

Answer 2

您有一張客戶表。 有開始日期，有時還有結束日期。 由於您想按日期分組，但表中有兩個日期，您需要先拆分這些日期。

然后，您可能有幾個月只有客戶來，而其他幾個月只有客戶離開。 因此，您需要兩個集合的完全外部連接。

對於累積總和（也稱為運行總計），請使用SUM OVER 。

with came as
(
  select date_trunc('month', date_start) as month, count(*) as cnt 
  from customer
  group by date_trunc('month', date_start)
)
, went as
(
  select date_trunc('month', date_end) as month, count(*) as cnt
  from customer
  where date_end is not null
  group by date_trunc('month', date_end)
)
select
  month,
  came.cnt as cust_new,
  went.cnt as cust_gone,
  sum(came.cnt - went.cnt) over (order by month) as cust_active
from came full outer join went using (month)
order by month;