用sql查询计算平均值

Question

我想知道从 2018 年 3 月开始每个用户的平均小时工资。我想用 SQL 查询来计算。

我有这样的数据：

开始日期表示小时工资的开始时间以及小时工资适用的新开始日期等。

结果应该是：

2 €10,65
4 €9,90

如何在 SQL 中执行此操作？

Answer 1

试试下面的查询。创建一个日历表，然后创建一个 cte 以添加缺失日期的缺失数据。一旦我们有了缺失日期的数据，WHERE 子句和GROUPBY 中的简单过滤器就可以工作了。

IF OBJECT_ID ('tempdb..#temp') IS NOT NULL
DROP TABLE #temp

IF OBJECT_ID('tempdb..#calendar') IS NOT NULL
    DROP TABLE #calendar;

CREATE TABLE #temp
(
UserId INT,
StartDate DATE,
HourlyWage decimal(10,2)
)

DECLARE @date DATE = '20180305'
INSERT INTO #temp VALUES 
(2,'20180205', 10.3),
(2,@date, 10.3),
(2,DATEADD(DAY,1,@date), 10.3),
(2,DATEADD(DAY,2,@date), 10.3),
(2,DATEADD(DAY,3,@date), 10.3),
(2,DATEADD(DAY,4,@date), 10.3),
(2,DATEADD(DAY,5,@date), 10.3),
(2,DATEADD(DAY,6,@date), 10.3),
(2,DATEADD(DAY,7,@date), 10.3),
(2,DATEADD(DAY,8,@date), 10.3),
(2,DATEADD(DAY,9,@date), 10.3),
(2,DATEADD(DAY,10,@date), 10.3),
(2,DATEADD(DAY,11,@date), 10.3),
(2,DATEADD(DAY,12,@date), 10.3),
(2,DATEADD(DAY,13,@date), 10.3),
(2,DATEADD(DAY,14,@date), 10.3),
(2,DATEADD(DAY,15,@date), 10.3),
(2,DATEADD(DAY,16,@date), 10.3),
(2,DATEADD(DAY,17,@date), 10.3),
(2,DATEADD(DAY,18,@date), 10.3),
(2,DATEADD(DAY,19,@date), 10.3),
(2,DATEADD(DAY,20,@date), 10.3),
(2,DATEADD(DAY,21,@date), 10.3),
(2,DATEADD(DAY,22,@date), 12.5),
(2,DATEADD(DAY,23,@date), 12.5),
(2,DATEADD(DAY,24,@date), 12.5),
(2,DATEADD(DAY,25,@date), 12.5),
(2,DATEADD(DAY,26,@date), 12.5),
(4,'20170221', 9.5),
(4,'20170301', 9.7),
(4,'20180227', 9.9)

DECLARE @FromDate DATETIME ,
        @ToDate DATETIME;

SELECT @FromDate = MIN(StartDate) ,
       @ToDate = MAX(StartDate)
FROM   #Temp;


SELECT   TOP ( DATEDIFF(day, @FromDate, @ToDate) + 1 ) calendarDate = CAST(DATEADD(
                                                                                 DAY ,
                                                                                 number ,
                                                                                 @FromDate) AS DATE) 
INTO     #calendar
FROM     [master].dbo.spt_values
WHERE    [type] = N'P'
ORDER BY number;

;WITH tempCTE
AS ( SELECT  DISTINCT t.userid ,
                      cal.calendarDate
     FROM    (   SELECT   calendarDate
                 FROM     #calendar c
                 ) cal
             CROSS JOIN (   SELECT UserId ,
                                   MIN(StartDate) OVER ( PARTITION BY UserId ) AS Mindate ,
                                   MAX(StartDate) OVER ( PARTITION BY UserId ) AS Maxdate 
                            FROM   #Temp ) t
     WHERE   cal.calendarDate
     BETWEEN t.Mindate AND t.Maxdate )

         SELECT   cal.UserId ,
         AVG(x.HourlyWage ) AS Avg_Wage
FROM     tempCTE cal
         CROSS APPLY (   SELECT   TOP 1 t.HourlyWage
                         FROM     #Temp t
                         WHERE    t.UserId = cal.UserId
                                  AND t.StartDate <= cal.calendarDate
                         ORDER BY t.StartDate DESC ) AS x
WHERE CalendarDate BETWEEN '20180301' AND '20180331' --your date filter here
GROUP BY cal.UserId

结果：

+--------+-----------+
| UserId | Avg_Wage  |
+--------+-----------+
|      2 | 10.654838 |
+--------+-----------+

Answer 2

以下查询将每个userid 的所有记录分组，然后计算平均值。对于分组，我们使用了group by 子句。

另外，MONTH 函数返回一个整数，表示指定日期的月份。由于您对 3 月感兴趣，所以我们将其与 3 进行比较。

Select UserId, avg(HourlyWage) 
from <<table>>
where month(StartDate) = 3
group by UserId

请记住将<<table>> 更改为实际表名。