用缺失期间的平均值填充列中缺失的行

Question

我有每个 ID 的每月累计计数器，但在某些月份计数器会丢失。我想根据缺失月份的时间段，用月平均值来填补这些缺失值。

我的桌子看起来像：

身份证	月	柜台
AAA	2023-09	1000
AAA	2023-10	-
AAA	2023-11	-
AAA	2023-12	4000
BBB	2022-11	2000
BBB	2022-12	-
BBB	2023-01	-
BBB	2022-02	-
BBB	2022-03	4000

我想要什么：

身份证	月	柜台
AAA	2023-09	1000
AAA	2023-10	2000
AAA	2023-11	3000
AAA	2023-12	4000
BBB	2022-11	2000
BBB	2022-12	2500
BBB	2023-01	3000
BBB	2022-02	3500
BBB	2022-03	4000

如何在 PostgreSQL 中完成此操作？

Answer 1

您通常可以使用窗口函数来计算 Counter 的缺失值，如以下查询所示：

SELECT id
     , month
     , counter
     , first_value(counter) OVER w
      + percent_rank() OVER w
      * ( last_value(counter) OVER w - first_value(counter) OVER w) AS new_counter
  FROM test
WINDOW w AS (PARTITION BY id ORDER BY month RANGE BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING)
 ORDER BY id, month

如果您想更新表，则可以在 UPDATE 函数中使用此查询：

With query AS
( SELECT id
     , month
     , first_value(counter) OVER w
      + percent_rank() OVER w
      * ( last_value(counter) OVER w - first_value(counter) OVER w) AS new_counter
  FROM test
WINDOW w AS (PARTITION BY id ORDER BY month RANGE BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING)
)
UPDATE test AS t
   SET counter = q.new_counter
  FROM query AS q
 WHERE t.id = q.id
   AND t.month = q.month
   AND counter IS null ;

请参阅 dbfiddle

中的演示