需要帮助为现有表创建视图，该视图中有一个datetime列，并且必须根据星期几和一天中的小时数将其划分为班次。例如，在工作日期间，班次应该在6、15和24之间，我的意思是从0到6夜班，从6到15上午，等等。
在Excel中，我已经完成了嵌套ifs的编写，但我不知道如何处理多例when语句。
IF([Day]="Monday";IF(AND([Hour]>=6;[Hour]<14);"Morning";IF(AND([Hour]>=14;[Hour]<22);"Afternoon";"N"));
IF([Day]="Wednesday";IF(AND([Hour]>=6;[Hour]<14);"Morning";IF(AND([Hour]>=14;[Hour]<22);"Afternoon";"N"));
IF([Day]="Friday";IF(AND([Hour]>=6;[Hour]<14);"Morning";IF(AND([Hour]>=14;[Hour]<22);"Afternoon";"N"));
ID Logtime Shift
-------------------------------
1 2019-10-17 00:05:00 Night
2 2019-10-17 05:55:00 Night
3 2019-10-17 06:05:00 Morning
4 2019-10-17 14:55:00 Morning
5 2019-10-17 15:05:00 Evening
6 2019-10-17 23:55:00 Evening
我可以使用以下代码完成一天的任务，但几天没有完成。
case
when DATENAME(WEEKDAY, LogTime) = 'Thursday' and DATEPART(hour, LogTime) < 6
then 'Night'
when DATENAME(WEEKDAY, LogTime) = 'Thursday' and DATEPART(hour, LogTime) >= 6 and DATEPART(hour, logtime) < 15
then 'Morning'
else 'Evening'
end as Shift
我希望有人可以提供帮助，并在此先多谢。
建议使用表格代替天数和班次，而不要使用复杂的案例陈述。
DECLARE @SampleData TABLE (ID INT, Logtime DATETIME)
INSERT INTO @SampleData VALUES
(1, '2019-10-17 00:05:00'),
(2, '2019-10-17 05:55:00'),
(3, '2019-10-17 06:05:00'),
(4, '2019-10-17 14:55:00'),
(5, '2019-10-17 15:05:00'),
(6, '2019-10-17 23:55:00')
SET DATEFIRST 1
SELECT T.*, Shifts.Shift FROM
@SampleData T
INNER JOIN (VALUES ( 1, 0, 6,'Night'), ( 1, 6, 15,'Morning'), ( 1, 15, 24,'Evening'),
( 2, 0, 6,'Night'), ( 2, 6, 15,'Morning'), ( 2, 15, 24,'Evening'),
( 3, 0, 6,'Night'), ( 3, 6, 15,'Morning'), ( 3, 15, 24,'Evening'),
( 4, 0, 6,'Night'), ( 4, 6, 15,'Morning'), ( 4, 15, 24,'Evening'),
( 5, 0, 6,'Night'), ( 5, 6, 15,'Morning'), ( 5, 15, 24,'Evening'),
( 6, 0, 6,'Night'), ( 6, 6, 15,'Morning'), ( 6, 15, 24,'Evening'),
( 7, 0, 6,'Night'), ( 7, 6, 15,'Morning'), ( 7, 15, 24,'Evening') ) Shifts(DayOfW, SDate, EDate, Shift) ON
DATEPART(WEEKDAY,T.Logtime) = Shifts.DayOfW
AND DATEPART(HOUR,T.Logtime) >= Shifts.SDate
AND DATEPART(HOUR,T.Logtime) < Shifts.EDate
结果：
ID Logtime Shift
----------- ----------------------- -------
1 2019-10-17 00:05:00.000 Night
2 2019-10-17 05:55:00.000 Night
3 2019-10-17 06:05:00.000 Morning
4 2019-10-17 14:55:00.000 Morning
5 2019-10-17 15:05:00.000 Evening
6 2019-10-17 23:55:00.000 Evening
简单的方法只是嵌套大小写，当....然后...结束时如下：
case DATENAME(WEEKDAY, @LogTime)
when 'Monday' then case when DATEPART(hour, @LogTime) < 6 then 'Night'
when DATEPART(hour, @LogTime) >= 6 and
DATEPART(hour, @LogTime) < 15 then 'Morning'
else 'Evening'
end
when 'Tuesday' then case when DATEPART(hour, @LogTime) < 6 then 'Night'
when DATEPART(hour, @LogTime) >= 6 and
DATEPART(hour, @LogTime) < 15 then 'Morning'
else 'Evening'
end
when 'Wednesday' then case when DATEPART(hour, @LogTime) < 6 then 'Night'
when DATEPART(hour, @LogTime) >= 6 and
DATEPART(hour, @LogTime) < 15 then 'Morning'
else 'Evening'
end
when 'Thursday' then case when DATEPART(hour, @LogTime) < 6 then 'Night'
when DATEPART(hour, @LogTime) >= 6 and
DATEPART(hour, @LogTime) < 15 then 'Morning'
else 'Evening'
end
when 'Friday' then case when DATEPART(hour, @LogTime) < 6 then 'Night'
when DATEPART(hour, @LogTime) >= 6 and
DATEPART(hour, @LogTime) < 15 then 'Morning'
else 'Evening'
end
else 'weekend'
end
但是为了避免重复模式，使用标量函数代替它会更优雅。
另一种看待它的方式是使用标量函数，如下所示
首先让我们创建一个返回班次名称的函数根据早上上班的开始时间和结束时间
IF OBJECT_ID ('ufn_DayPart', 'FN') IS NOT NULL
DROP FUNCTION ufn_DayPart;
GO
CREATE FUNCTION ufn_DayPart(
@LogTime datetime,
@MorningShiftStart int,
@MorningShiftEnd int)
RETURNS
VARCHAR(10)AS
BEGIN
RETURN CASE WHEN DATEPART(hour, @LogTime) < @MorningShiftStart then 'Night'
WHEN DATEPART(hour, @LogTime) >= @MorningShiftStart and
DATEPART(hour, @LogTime) < @MorningShiftEnd then 'Morning'
else 'Evening'
END
END
GO
现在将其放在一周的角度来看让我们创建一个函数，其中移位可以开始或结束在不同的时间，具体取决于星期几
IF OBJECT_ID ('ufn_GetShift', 'FN') IS NOT NULL
DROP FUNCTION ufn_GetShift;
GO
CREATE FUNCTION ufn_GetShift(
@LogTime datetime)
RETURNS
VARCHAR(10)AS
BEGIN
RETURN case DATENAME(WEEKDAY, @LogTime)
when 'Monday' then dbo.ufn_DayPart(@LogTime, 6, 15 )
when 'Tuesday' then dbo.ufn_DayPart(@LogTime, 6, 15 )
when 'Wednesday' then dbo.ufn_DayPart(@LogTime, 6, 15 )
when 'Thursday' then dbo.ufn_DayPart(@LogTime, 6, 15 )
when 'Friday' then dbo.ufn_DayPart(@LogTime, 6, 15 )
else 'weekend'
END
END
GO
现在，让我们在非常简单的查询中尝试一下：
begin
declare @LogTime as datetime
set @LogTime = '2019-09-29 01:10' SELECT @LogTime, dbo.ufn_GetShift(@LogTime) as shift
set @LogTime = '2019-09-30 20:10' SELECT @LogTime, dbo.ufn_GetShift(@LogTime) as shift
set @LogTime = '2019-10-01 12:10' SELECT @LogTime, dbo.ufn_GetShift(@LogTime) as shift
set @LogTime = '2019-10-02 06:00' SELECT @LogTime, dbo.ufn_GetShift(@LogTime) as shift
set @LogTime = '2019-10-02 05:59:59' SELECT @LogTime, dbo.ufn_GetShift(@LogTime) as shift
set @LogTime = '2019-10-03 19:10' SELECT @LogTime, dbo.ufn_GetShift(@LogTime) as shift
end
在您的查询中，它看起来像：
SELECT col_1, col_2, dbo.ufn_GetShift(col_timeLog) as shift
FROM YourTable
我希望我能这样更清楚地阐明