在 PostgreSQL 中为按日期设置的唯一组添加缺失的行

Question

我有一个 table，其中包含 game_id、category 日期列，表示 activity 月份的第一天 [=15] =]，一共 amount.

在某些月份，game_id 和 date_month 缺少类别，我需要为每个 table 的整个 table 中缺少的唯一组集填充这些缺少的行每场比赛一个月。

举个例子：

CREATE TEMPORARY TABLE activity (
  game_id INT,
  category TEXT, 
  date DATE,
  amount INT
);

INSERT INTO activity (game_id, category, date, amount) VALUES 
  (1, 'Up', '2015-12-01', 9)
, (1, 'Down', '2015-12-01', 12)
-- Left Missing for '2015-12-01
-- Right Missing for '2015-12-01
, (1, 'Up', '2016-01-01', 12)
,  (1, 'Down', '2016-01-01', 4)
,  (1, 'Left', '2016-01-01', 7)
,  (1, 'Right', '2016-01-01', 3)
,  (1, 'Up', '2016-02-01', 3)
,  (1, 'Down', '2016-02-01', 11)
,  (1, 'Left', '2016-02-01', 4)
,  (1, 'Right', '2016-02-01', 8)
,  (1, 'Up', '2016-03-01', 3)
,  (1, 'Down', '2016-03-01', 11)
-- Left Missing for '2016-03-01'
,  (1, 'Right', '2016-03-01', 8)
,  (1, 'Up', '2016-04-01', 3)
,  (1, 'Down', '2016-04-01', 11)
,  (1, 'Left', '2016-04-01', 4)
-- Right Missing for '2016-04-01'
,  (2, 'Up', '2020-12-01', 9)
, (2, 'Down', '2020-12-01', 12)
-- Left Missing for '2020-12-01'
-- Right Missing for '2020-12-01'
, (2, 'Up', '2020-01-01', 12)
,  (2, 'Down', '2020-01-01', 4)
,  (2, 'Left', '2020-01-01', 7)
-- Right Missing for '2020-01-01'
;

在这种情况下，需要使用 0 金额创建以下缺失值，game_id 可以有一组不同的日期范围。

(1, 'Left', '2015-12-01', 0)
(1, 'Right', '2015-12-01', 0)
(1, 'Left', '2016-03-01', 0)
(1, 'Right', '2016-04-01', 0)
(2, 'Left', '2020-12-01', 0)
(2, 'Right', '2020-12-01', 0)
(2, 'Right', '2020-01-01', 0)

到目前为止，我的尝试是打算在 UNION 中使用它回到主要 table。这不会产生任何行，因为不会生成超出其最小和最大日期范围的缺失组。

SELECT
    game_id,
    category,
    generate_series(
        min(date_month),
        max(date_month),
        '1month'
        )::date AS date_month,
    0 as amount
FROM activity
WHERE NOT EXISTS (
    SELECT
        1
    FROM activity
    WHERE game_id=game_id AND category=category AND date_month=date_month
) 
GROUP BY 1,2
ORDER BY game_id, date_month

Answer 1

您必须 CROSS 将 table 的不同 game_id 和 date 组合加入 table 的不同 category 和然后 LEFT 加入 table:

SELECT d.game_id, c.category, d.date, COALESCE(a.amount, 0) amount
FROM (SELECT DISTINCT game_id, date FROM activity) d
CROSS JOIN (SELECT DISTINCT category FROM activity) c
LEFT JOIN activity a 
ON a.game_id = d.game_id AND a.date = d.date AND a.category = c.category
ORDER BY d.game_id, d.date

如果要在 table 中插入缺失的行：

INSERT INTO activity (game_id, category, date, amount)
SELECT d.game_id, c.category, d.date, 0
FROM (SELECT DISTINCT game_id, date FROM activity) d
CROSS JOIN (SELECT DISTINCT category FROM activity) c
LEFT JOIN activity a 
ON a.game_id = d.game_id AND a.date = d.date AND a.category = c.category
WHERE a.game_id IS NULL

参见demo。

在 PostgreSQL 中为按日期设置的唯一组添加缺失的行

Add missing rows for a unique group set by date in PostgreSQL

postgresql

group-by

aggregate-functions

missing-data

generate-series