如何在 Presto 的 SQL (Athena) 中计算从一年开始的每个月的平均值？

Question

下面是我拥有的 table 数据的示例

| date       | value |
| 2020-01-01 |  20   |
| 2020-01-14 |  10   |
| 2020-02-02 |  30   |
| 2020-02-11 |  25   |
| 2020-02-25 |  25   |
| 2020-03-13 |  34   |
| 2020-03-21 |  10   |
| 2020-04-06 |  55   |
| 2020-04-07 |  11   |

我想生成如下结果集

| date       | value |  average                       |
| 2020-01-01 |  20   |  Jan average                   |
| 2020-01-14 |  10   |  Jan average                   |   
| 2020-02-02 |  30   |  Jan & Feb average             |
| 2020-02-11 |  25   |  Jan & Feb average             |
| 2020-02-25 |  25   |  Jan & Feb average             |
| 2020-03-13 |  34   |  Jan & Feb & Mar average       |
| 2020-03-21 |  10   |  Jan & Feb & Mar average       |
| 2020-04-06 |  55   |  Jan & Feb & Mar & Apr average |
| 2020-04-07 |  11   |  Jan & Feb & Mar & Apr average |

我尝试使用 window 函数 OVER() 和 PARTITION() 但我设法按月而不是从年开始计算平均值。

有什么建议，请。

谢谢

Answer 1

我想你想要：

select 
    t.*,
    avg(value) over(
        partition by year(date)
        order by month(date)
    ) running_avg
from mytable t

这会将每年放在一个单独的分区中，顺序按月对行进行分区。

Answer 2

不确定我是否理解你的问题，但如果你想要的只是运行每一行按年份计算的平均值：

SELECT date, value, (
  SELECT AVG(value)
  FROM data ds
  WHERE ds.date <= d.date AND YEAR(ds.date) = YEAR(d.date)
) average
FROM data d
ORDER BY d.date ASC;

Example with MySQL（此特定查询的语法相同）

如果要在平均值中包含同一个月的后面的行，请使用 WHERE MONTH(ds.date) <= MONTH(d.date)。

Answer 3

下面的查询应该给出您预期的输出-

Demo Here

SELECT A.*,
(
    SELECT AVG(Value * 1.00) 
    FROM your_table B 
    WHERE YEAR(B.Date) = YEAR(A.DAte) 
    AND MONTH(B.Date) <= MONTH(A.DAte)
)
FROM your_table A

这个查询将使你每年的产出。但是，如果您不想按 YEAR 进行分区，只需从子查询中删除 YEAR 过滤器即可。

下面的查询将 return AVG 不考虑 YEAR，只是几个月之前的所有 AVG -

Demo Here

SELECT A.*,
(
    SELECT AVG(Value * 1.00) 
    FROM your_table B 
    WHERE B.date <= 
    (
        SELECT MAX(Date) 
        FROM your_table C
        WHERE YEAR(c.Date) = YEAR(A.Date)
        AND MONTH(C.Date) = MONTH(A.Date)
    )
)
FROM your_table A

Answer 4

SELECT a.date,
    a.value,
     (Select avg(b.value) from myTable B where b.date < a.date and YEAR(a.date) = YEAR(b.date)) 
From myTable a

如何在 Presto 的 SQL (Athena) 中计算从一年开始的每个月的平均值？

How to calculate average for every month from start from year in Presto's SQL (Athena)?

sql

select

window-functions

presto

amazon-athena