Question

我有一张表格如下

Day_No  Average  Count
------ -------- ------
1       7.5      12
2       12       15
3       15       4
4       13       14
5       6.5      12
6       21       17
7       15       4
8       11       15
9       15       11
10      10       13
11      9        40
12      13       12
.
.
.
.
.

我想生成7天移动平均线。我已经看到每天都有相同权重的解决方案，但显然每个平均需要根据计数进行加权。有什么建议吗？

Answer 1

我不完全确定你想要达到的目标。也许这就是你想要的：

select day_no,
       average,
       cnt,
       avg(average * cnt) over (order by day_no rows between 7 preceding and current row) as running_avg
from data
order by day_no;

rows between 7 preceding and current row子句假定结果中每天有一行。

（请注意，我对cnt列使用了count，因为使用保留字作为列名称不是一个好主意。）

SQLFiddle示例：http://sqlfiddle.com/#!4/fa0a84/1

Answer 2

解决！需要将平均值和计数的乘积相加，然后除以范围内的计数。

select day_no,
       average,
       cnt,
       sum(average * cnt) over (order by day_no rows between 7 preceding and current row)/sum(cnt) over (order by day_no rows between 7 preceding and current row) as running_avg
from data
order by day_no;

感谢horse_with_no_name让我走上正轨

Answer 3

select initial_data.full_sum/initial_data.fullCount as the_avg
from
    (select
      sum(Average * count) as full_sum,
      sum(count) as full_count
    from the_table
    group by <the grouping condition>) initial_data

像这样的东西。不记得所有组和算术的正确oracle语法

Answer 4

我会尝试以下查询：

select Day_No day, 
   (select sum(Average*Count)/sum(Count) 
      from table 
      where Day_No between day-7 and day) 
from table;

具有可变权重的移动平均线的SQL

4 个答案: