Sql 计算有条件的一段时间内的人数

我们有一个关于课程中用户信息的表格

CREATE TABLE public.students
(
    student_id integer NOT NULL DEFAULT nextval('students_student_id_seq'::regclass),
    timest timestamp without time zone NOT NULL   ##
    is_correct BOOLEAN NOT NULL,
    CONSTRAINT students_pkey PRIMARY KEY (student_id)
)

“成功”学生，当月至少一次在一小时内正确完成10个练习。 帮助查询2020年10月的成功学生人数

试图找出一小时内连续解决的练习数。为此，我计算了交换和，它小于3600

WITH timediff AS (
     SELECT *,
         LEAD(timest) OVER w AS next_time,
         LEAD(timest) OVER w - timest AS diff
     FROM payment
     WHERE is_correct IS TRUE
     WINDOW w AS (PARTITION  BY student_id ORDER BY timest 
     ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING))

SELECT *,
    CASE  
    WHEN (sum(diff) OVER q) > '3600' 
    THEN diff 
    ELSE (sum(diff) OWER q) 
    END cum_sum
FROM timediff
WINDOW q AS (PARTITION  by student_id ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW)

那么我不知道如何计算连续周期。我认为这不是最好的选择。 请帮忙处理你的请求

“成功”学生，当月至少一次在一小时内正确完成10个练习

如果我没有弄错，您可以使用窗口功能和范围框：

select count(distinct student_id) cnt_successful_students
from (
    select s.*,
        count(*) filter(where is_correct) over(
            partition by student_id 
            order by timest
            range between interval '1 hour' preceding and current row
        ) cnt
    from students s
    where timest >= date_trunc('month', current_date) 
      and timest <  date_trunc('month', current_date) + interval '1 month'
) s
where cnt >= 10

子查询将筛选当前月份。对于每一行，窗口函数计算同一学生在最后一小时内成功练习的次数。外部查询然后过滤至少一次达到阈值的学生

“成功”学生，当月至少一次在一小时内正确完成10个练习

如果我没有弄错，您可以使用窗口功能和范围框：

select count(distinct student_id) cnt_successful_students
from (
    select s.*,
        count(*) filter(where is_correct) over(
            partition by student_id 
            order by timest
            range between interval '1 hour' preceding and current row
        ) cnt
    from students s
    where timest >= date_trunc('month', current_date) 
      and timest <  date_trunc('month', current_date) + interval '1 month'
) s
where cnt >= 10

---

子查询将筛选当前月份。对于每一行，窗口函数计算同一学生在最后一小时内成功练习的次数。然后外部查询筛选至少一次达到阈值的学生。

代码显然是Postgres，因此我删除了SQL Server标记。示例数据和期望的结果也会使您的问题更加清晰。代码显然是Postgres，因此我删除了SQL Server标记。样本数据和期望的结果也会让你的问题更加清晰。