Question

好吧，所以我是SQL的新手，这就是为什么我问这个问题。

我有一个表，名为： kpi_notification_metrics_per_month 该表有2列：

日期
NotificationCount

我想创建一个将显示的全新表格

平均值
中位数
模式

对于NotificationCount列。

示例表：

Date    NotificationCount
01/04/2018 00:00    0
31/03/2018 00:00    0
25/03/2018 00:00    0
24/03/2018 00:00    0
22/03/2018 00:00    0
18/03/2018 00:00    0
17/03/2018 00:00    0
14/03/2018 00:00    0
11/03/2018 00:00    0
07/04/2018 00:00    1
26/03/2018 00:00    1
21/03/2018 00:00    1
15/03/2018 00:00    1
13/03/2018 00:00    1
12/03/2018 00:00    1
10/03/2018 00:00    1
08/04/2018 00:00    2
30/03/2018 00:00    2
09/03/2018 00:00    2
08/03/2018 00:00    2
20/03/2018 00:00    3
19/03/2018 00:00    4
02/04/2018 00:00    9
23/03/2018 00:00    11
27/03/2018 00:00    22
03/04/2018 00:00    28
28/03/2018 00:00    34
04/04/2018 00:00    39
05/04/2018 00:00    43
29/03/2018 00:00    47
06/04/2018 00:00    50
16/03/2018 00:00    140

预期结果：

Mean    Median  Mode
13.90625    1   0

Answer 1

平均值：使用Avg()

Select Avg(NotificationCount)
From   kpi_notification_metrics_per_month

中位数：按ASC和DESC对TOP 50 Percent的数据进行排序，找到中间的数据。

Select ((
        Select Top 1 NotificationCount
        From   (
                Select  Top 50 Percent NotificationCount
                From    kpi_notification_metrics_per_month
                Where   NotificationCount Is NOT NULL
                Order By NotificationCount
                ) As A
        Order By NotificationCountDESC) + 
        (
        Select Top 1 NotificationCount
        From   (
                Select  Top 50 Percent NotificationCount
                From    kpi_notification_metrics_per_month
                Where   NotificationCount Is NOT NULL
                Order By NotificationCount DESC
                ) As A
        Order By NotificationCount Asc)) / 2

模式：获取每个值集的计数并以DESC顺序获取前1行。

SELECT TOP 1 with ties NotificationCount
FROM   kpi_notification_metrics_per_month
WHERE  NotificationCount IS Not NULL
GROUP  BY NotificationCount
ORDER  BY COUNT(*) DESC

所有工作在Sql Server 2014中。

参考：http://blogs.lessthandot.com/index.php/datamgmt/datadesign/calculating-mean-median-and-mode-with-sq/

Answer 2

这是在Oracle中执行此操作的方法：

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return conn;

不需要另一个表。您可以（并且应该）始终临时查询数据。为了方便起见，您可以按照jarlh在请求注释中建议的方式创建视图。

如何使用均值，中位数和众数创建新的SQL表？

2 个答案: