如何使用SQL从汇总结果计算每日平均值？

Question

我正在输出一些数据，我想获取一些数字的每日平均值。

正如您所看到的，我要做的是计算接收/结果的行数（考虑行ID），然后将其除以日值以得出每日平均值。（30/1），（64 / 2）等我已经尝试了所有方法，但与此同时我一直碰壁。

就目前而言，我猜测是要使此工作成为某种子查询。我只是不知道该如何获取日期（行编号1,2,3,4等）用于除法。

SELECT calendar_date, SUM(NY_dayscore * cAttendance) 
FROM  vw_Appointments 
WHERE status = 'Confirmed'
Group by calendar_date  

尝试计数有区别，无济于事

SUM(NY_dayscore * cAttendance) ) / count(distinct calendar_date)

我的原始代码很长，请cba将其全部发布。因此，只需尝试发布少量示例代码以获取有关该问题的指导。

Answer 1

我认为您需要sum(showed) over (..)/row_number() over (..)

WITH Table1(date, showed) AS
(
 SELECT '2019-01-02', 30 UNION ALL
 SELECT '2019-01-03', 34 UNION ALL
 SELECT '2019-01-03', 41 UNION ALL
 SELECT '2019-01-04', 48
)
SELECT date, 
       sum(showed) over (order by date) / 
       row_number() over (order by date)
       as daily_average
 FROM Table1
GROUP BY showed, date;

date        daily_average
2019-01-02  30
2019-01-03  52
2019-01-03  35
2019-01-04  38

Demo

Answer 2

是ROW_NUMBER()失踪了吗？

SELECT 
  calendar_date, 
  SUM(NY_dayscore * cAttendance) / (ROW_NUMBER() OVER (ORDER BY calendar_date ASC)) AS average
FROM  vw_Appointments 
WHERE status = 'Confirmed'
GROUP BY calendar_date
ORDER BY calendar_date

Answer 3

在SQL Server 2012+中，您将使用累计平均值：

/home/pi/Desktop/MelloBot/commands/pat.js:72
help: `<usermention> / Your daily dose of pat`
                     ^

SyntaxError: Invalid regular expression: missing /
at createScript (vm.js:80:10)
at Object.runInThisContext (vm.js:139:10)
at Module._compile (module.js:616:28)
at Object.Module._extensions..js (module.js:663:10)
at Module.load (module.js:565:32)
at tryModuleLoad (module.js:505:12)
at Function.Module._load (module.js:497:3)
at Module.require (module.js:596:17)
at reloadParent (/home/pi/Desktop/MelloBot/node_modules/require- 
reload/reload.js:29:23)
at reload (/home/pi/Desktop/MelloBot/node_modules/require- 
reload/reload.js:59:12)

在SQL Server 2008中，这更加困难：

select calendar_date, sum(NY_dayscore * cAttendance),
       avg(sum(NY_dayscore * cAttendance)) over (order by calendar_date) as running_average
from vw_appointments a
where status = 'Confirmed'
group by calendar_date
order by calendar_date;