Sql将楼层应用于日期时间，其中楼层不是标准的，例如每2小时，每2天等

Question

目标：Sql将楼层应用于日期时间，其中楼层不是标准的，例如每隔2小时，每3天一次。而不是标准每小时，每天等。

通用目的：为每个收集期间的数据进行比较。当收集期间大于标准时间单位时。同时保留Datetime类型的好处。

转换示例：

将日期时间设为2小时

+==========================+=======================+
|        WhenCreated       |       Time_Slot       |
+==========================+=======================+
|   2019-02-28 00:34:00    | 2019-02-28 00:00:00   |
+--------------------------+-----------------------+
|   2019-02-28 01:34:00    | 2019-02-28 00:00:00   |
+--------------------------+-----------------------+
|   2019-02-28 02:00:00    | 2019-02-28 02:00:00   |
+--------------------------+-----------------------+
|   2019-02-28 02:20:00    | 2019-02-28 02:00:00   |
+--------------------------+-----------------------+
|   2019-02-28 03:59:00    | 2019-02-28 02:00:00   |
+--------------------------+-----------------------+

当前解决方案

在select语句中将根据[WhenCreated]创建一个新列[Time_Slot]：

left(convert(varchar(30), WhenCreated, 102),4) + '-' + left(right(convert(varchar(30), WhenCreated, 102),5),2) + '-' + right(convert(varchar(30), WhenCreated, 102),2) + ' ' +
    case
        when left(cast(cast(WhenCreated as time) as varchar(30)),2) in ('00','01') then '00:00:00.000'
        when left(cast(cast(WhenCreated as time) as varchar(30)),2) in ('02','03') then '02:00:00.000'
        when left(cast(cast(WhenCreated as time) as varchar(30)),2) in ('04','05') then '04:00:00.000'
        when left(cast(cast(WhenCreated as time) as varchar(30)),2) in ('06','07') then '06:00:00.000'
        when left(cast(cast(WhenCreated as time) as varchar(30)),2) in ('08','09') then '08:00:00.000'
        when left(cast(cast(WhenCreated as time) as varchar(30)),2) in ('10','11') then '10:00:00.000'
        when left(cast(cast(WhenCreated as time) as varchar(30)),2) in ('12','13') then '12:00:00.000'
        when left(cast(cast(WhenCreated as time) as varchar(30)),2) in ('14','15') then '14:00:00.000'
        when left(cast(cast(WhenCreated as time) as varchar(30)),2) in ('16','17') then '16:00:00.000'
        when left(cast(cast(WhenCreated as time) as varchar(30)),2) in ('18','19') then '18:00:00.000'
        when left(cast(cast(WhenCreated as time) as varchar(30)),2) in ('20','21') then '20:00:00.000'
        when left(cast(cast(WhenCreated as time) as varchar(30)),2) in ('22','23') then '22:00:00.000'
    end as [Time_Slot]

当前的挑战：当前的解决方案有效，但它很混乱。必须有一个更简单的方法。那么有什么更好的方法呢？

编辑：表中的修复错误。

Answer 1

将日期解构为其零件，然后使用必要的零件重新构造它，调整需要铺设的零件。

要将整数值置于乘数，只需除以乘数并再次乘以它。这依赖于整数除法截断除法结果，例如5 / 2 = 2，所以5 / 2 * 2 = 4，即截断为2的倍数。

因此，将WhenCreated值降至2小时的倍数：

DATETIMEFROMPARTS ( YEAR(WhenCreated), MONTH(WhenCreated), DAY(WhenCreated),
                    DATEPART(HOUR, WhenCreated) / 2 * 2, /*min*/0, /*sec*/0, /*milli*/0 )