Sql 一些示例值也会有很大帮助。您好@ErwinBrandstetter我已按要求添加了表定义和示例值。：）谢谢你能解释一下吗？我在子查询中迷失了方向，尤其是关于“第6-7天*w作为w_开始”和“第7天*w作为w_结束”的部分@christinang89：为主要

---

一些示例值也会有很大帮助。您好@ErwinBrandstetter我已按要求添加了表定义和示例值。：）谢谢你能解释一下吗？我在子查询中迷失了方向，尤其是关于“第6-7天*w作为w_开始”和“第7天*w作为w_结束”的部分@christinang89：为主要问题添加了解决方案和史诗般的解释。感谢您的史诗般解释@ErwinBrandstetter！！像这样的答案让我如此热爱SO社区：）@christinang89:添加了更多优化。特别是，尽早排除“不可能”的用户，以减少处理的行数。还有最新的小提琴。

CREATE TABLE requests (
  id text PRIMARY KEY, -- id of the request
  amount bigint,       -- sum of requests made by accounts_id to recipient_id,
                       -- aggregated on a daily basis based on "date"
  accounts_id text,    -- id of the user
  recipient_id text,   -- id of the recipient
  date timestamp       -- date that the request was made in YYYY-MM-DD
);

INSERT INTO requests2
VALUES
    ('1',  19, 'a1', 'b1', '2014-10-05 00:00:00'),
    ('2',  19, 'a2', 'b2', '2014-10-06 00:00:00'),
    ('3',  85, 'a3', 'b3', '2014-10-07 00:00:00'),
    ('4',  11, 'a1', 'b4', '2014-10-13 00:00:00'),
    ('5',  2,  'a2', 'b5', '2014-10-14 00:00:00'),
    ('6',  50, 'a3', 'b5', '2014-10-15 00:00:00'),
    ('7',  787323, 'a1', 'b6', '2014-10-17 00:00:00'),
    ('8',  33, 'a2', 'b8', '2014-10-18 00:00:00'),
    ('9',  14, 'a3', 'b9', '2014-10-19 00:00:00'),
    ('10', 11, 'a4', 'b10', '2014-10-19 00:00:00'),
    ('11', 1628, 'a1', 'b11', '2014-10-25 00:00:00'),
    ('13', 101, 'a2', 'b11', '2014-10-25 00:00:00');

Date       | # Active users
-----------+---------------
10-01-2014 | 600
10-02-2014 | 703
10-03-2014 | 891

SELECT count(*)
FROM
  (SELECT accounts_id
   FROM requests
   WHERE "date" BETWEEN '2014-10-01'::date - interval '2 weeks' AND '2014-10-01'::date - interval '1 week'
   GROUP BY accounts_id HAVING sum(amount) > 10) week_1
JOIN
  (SELECT accounts_id
   FROM requests
   WHERE "date" BETWEEN '2014-10-01'::date - interval '3 weeks' AND '2014-10-01'::date - interval '2 week'
   GROUP BY accounts_id HAVING sum(amount) > 10) week_2 ON week_1.accounts_id = week_2.accounts_id
JOIN
  (SELECT accounts_id
   FROM requests
   WHERE "date" BETWEEN '2014-10-01'::date - interval '4 weeks' AND '2014-10-01'::date - interval '3 week'
   GROUP BY accounts_id HAVING sum(amount) > 10) week_3 ON week_2.accounts_id = week_3.accounts_id
JOIN
  (SELECT accounts_id
   FROM requests
   WHERE "date" BETWEEN '2014-10-01'::date - interval '5 weeks' AND '2014-10-01'::date - interval '4 week'
   GROUP BY accounts_id HAVING sum(amount) > 10) week_4 ON week_3.accounts_id = week_4.accounts_id

SELECT week_1."Date_series",
       count(*)
FROM
  (SELECT to_char(DAY::date, 'YYYY-MM-DD') AS "Date_series",
          accounts_id
   FROM generate_series('2014-10-01'::date, CURRENT_DATE, '1 day') DAY, requests
   WHERE to_char(DAY::date, 'YYYY-MM-DD')::date BETWEEN requests.date::date - interval '2 weeks' AND requests.date::date - interval '1 week'
   GROUP BY "Date_series",
            accounts_id HAVING sum(amount) > 10) week_1
JOIN
  (SELECT to_char(DAY::date, 'YYYY-MM-DD') AS "Date_series",
          accounts_id
   FROM generate_series('2014-10-01'::date, CURRENT_DATE, '1 day') DAY, requests
   WHERE to_char(DAY::date, 'YYYY-MM-DD')::date BETWEEN requests.date::date - interval '3 weeks' AND requests.date::date - interval '2 week'
   GROUP BY "Date_series",
            accounts_id HAVING sum(amount) > 10) week_2 ON week_1.accounts_id = week_2.accounts_id
AND week_1."Date_series" = week_2."Date_series"
JOIN
  (SELECT to_char(DAY::date, 'YYYY-MM-DD') AS "Date_series",
          accounts_id
   FROM generate_series('2014-10-01'::date, CURRENT_DATE, '1 day') DAY, requests
   WHERE to_char(DAY::date, 'YYYY-MM-DD')::date BETWEEN requests.date::date - interval '4 weeks' AND requests.date::date - interval '3 week'
   GROUP BY "Date_series",
            accounts_id HAVING sum(amount) > 10) week_3 ON week_2.accounts_id = week_3.accounts_id
AND week_2."Date_series" = week_3."Date_series"
JOIN
  (SELECT to_char(DAY::date, 'YYYY-MM-DD') AS "Date_series",
          accounts_id
   FROM generate_series('2014-10-01'::date, CURRENT_DATE, '1 day') DAY, requests
   WHERE to_char(DAY::date, 'YYYY-MM-DD')::date BETWEEN requests.date::date - interval '5 weeks' AND requests.date::date - interval '4 week'
   GROUP BY "Date_series",
            accounts_id HAVING sum(amount) > 10) week_4 ON week_3.accounts_id = week_4.accounts_id
AND week_3."Date_series" = week_4."Date_series"
GROUP BY week_1."Date_series"

CREATE TABLE requests (
   id           int
 , accounts_id  int  -- (id of the user)
 , recipient_id int  -- (id of the recipient)
 , date         date -- (date that the request was made in YYYY-MM-DD)
 , amount       int  -- (# of requests by accounts_id for the day)
);

SELECT accounts_id
FROM  (
   SELECT w.w, r.accounts_id
   FROM  (
      SELECT w
           , day - 6 - 7 * w AS w_start
           , day     - 7 * w AS w_end   
      FROM  (SELECT '2014-10-31'::date - 1 AS day) d  -- effective date here
           , generate_series(0,3) w
      ) w
   JOIN   requests r ON r."date" BETWEEN w_start AND w_end
   GROUP  BY w.w, r.accounts_id
   HAVING sum(r.amount) > 10
   ) sub
GROUP  BY 1
HAVING count(*) = 4;

CREATE FUNCTION f_active_users (_now date = now()::date, _days int = 3)
  RETURNS TABLE (day date, users int) AS
$func$
WITH r AS (
   SELECT accounts_id, date, sum(amount)::int AS amount
   FROM   requests
   WHERE  date BETWEEN _now - (27 + _days) AND _now - 1
   GROUP  BY accounts_id, date
   )
SELECT date + 1, count(w_ct = 4 OR NULL)::int
FROM  (
   SELECT accounts_id, date
        , count(w_amount > 10 OR NULL)
                         OVER (PARTITION BY accounts_id, dow ORDER BY date DESC
                         ROWS BETWEEN CURRENT ROW AND 3 FOLLOWING) AS w_ct
   FROM  (
      SELECT accounts_id, date, dow   
           , sum(amount) OVER (PARTITION BY accounts_id ORDER BY date DESC
                         ROWS BETWEEN CURRENT ROW AND 6 FOLLOWING) AS w_amount
      FROM  (SELECT _now - i AS date, i%7 AS dow
             FROM   generate_series(1, 27 + _days) i) d -- period of interest
      CROSS  JOIN (
             SELECT accounts_id FROM r
             GROUP  BY 1
             HAVING count(*) > 3 AND sum(amount) > 39  -- enough rows & requests
             AND    max(date) > min(date) + 15) a      -- can cover 4 weeks
      LEFT   JOIN r USING (accounts_id, date)
      ) sub1
   WHERE date > _now - (22 + _days)  -- cut off 6 trailing days now - useful?
   ) sub2
GROUP  BY date
ORDER  BY date DESC
LIMIT  _days
$func$ LANGUAGE sql STABLE;

SELECT * FROM f_active_users('2014-10-31', 5);

SELECT * FROM f_active_users();

CREATE INDEX foo ON requests (date, accounts_id, amount);