我正在做一些SQL选择查询,并希望将我的UTC日期时间列转换为本地时间,以便在我的查询结果中显示为本地时间。注意,我不希望通过代码进行这种转换,而是当我对我的数据库进行手动和随机SQL查询时。


当前回答

对于任何仍然试图解决这个问题的人,这里有一个在SQL Server 2017中工作的概念证明

 declare
    @StartDate date = '2020-01-01'

;with cte_utc as
(
    select 
         1 as i
        ,CONVERT(datetime, @StartDate) AS UTC
        ,datepart(weekday, CONVERT(datetime, @StartDate)) as Weekday
        ,datepart(month, CONVERT(datetime, @StartDate)) as [Month]
        ,datepart(YEAR, CONVERT(datetime, @StartDate)) as [Year]
        
    union all

    Select
         i + 1
        ,dateadd(d, 1, utc)
        ,datepart(weekday, CONVERT(datetime, dateadd(d, 1, utc))) as Weekday
        ,datepart(month, CONVERT(datetime, dateadd(d, 1, utc))) as [Month]
        ,datepart(YEAR, CONVERT(datetime, dateadd(d, 1, utc))) as [Year]
    from    
        cte_utc
    where
        (i + 1) < 32767

), cte_utc_dates as 
(
    select 
        *,
        DENSE_RANK()OVER(PARTITION BY [Year], [Month], [Weekday] ORDER BY Utc) WeekDayIndex
    from
        cte_utc

), cte_hours as (
    select 0 as [Hour]
    union all
    select [Hour] + 1 from cte_hours where [Hour] < 23
)

select
    d.*
    , DATEADD(hour, h.Hour, d.UTC) AS UtcTime
    ,CONVERT(datetime, DATEADD(hour, h.Hour, d.UTC) AT TIME ZONE 'UTC' AT TIME ZONE 'Central Standard Time') CST
    ,CONVERT(datetime, DATEADD(hour, h.Hour, d.UTC) AT TIME ZONE 'UTC' AT TIME ZONE 'Eastern Standard Time') EST
from
    cte_utc_dates d, cte_hours h
where
    ([Month] = 3 and [Weekday] = 1 and WeekDayIndex = 2 )-- dst start
    or 
    ([Month] = 11 and [Weekday] = 1 and WeekDayIndex = 1 )-- dst end
order by
    utc
OPTION (MAXRECURSION 32767)

GO

其他回答

最简单的答案并不总是在底部,但这一次是,并且可以在上面的评论中看到。 使用您自己的“AT TIME ZONE”来捕获列/数据字段的TzOffset,而不是当前的SYSDATETIME。 在下面的数据中,2个查询,一个关于feb数据(DST是关闭的,在阿姆斯特丹的冬天)+1差异 第二次查询阿姆斯特丹4月份的数据,所以+2小时的差异。

    select top 2 month(receiveTimeUTC) as MonthInWinterOrSpring
   ,  receiveTimeUTC
   ,  CONVERT(datetime,  SWITCHOFFSET(CONVERT(datetimeoffset,  receiveTimeUTC),  DATENAME(TzOffset, SYSDATETIMEOFFSET()))) as LocalTimeWrongNoDST
   ,  CONVERT(datetime,  SWITCHOFFSET(CONVERT(datetimeoffset,  receiveTimeUTC),  DATENAME(TzOffset, receiveTimeUTC  AT TIME ZONE 'Central European Standard Time' ))) as LocalTimeWithDST
       from sensordetails order by id

    select top 2 month(receiveTimeUTC) as MonthInWinterOrSpring, receiveTimeUTC
,  CONVERT(datetime,  SWITCHOFFSET(CONVERT(datetimeoffset,  receiveTimeUTC),  DATENAME(TzOffset, SYSDATETIMEOFFSET()))) as LocalTimeWrongNoDST
,  CONVERT(datetime,  SWITCHOFFSET(CONVERT(datetimeoffset,  receiveTimeUTC),  DATENAME(TzOffset, receiveTimeUTC  AT TIME ZONE 'Central European Standard Time' ))) as LocalTimeWithDST
       from sensordetails order by id desc

结果:

所以这是一个T-SQL (SQL Server Answer),不需要函数的storedproc。

使用新的SQL Server 2016机会:

CREATE FUNCTION ToLocalTime(@dtUtc datetime, @timezoneId nvarchar(256))
RETURNS datetime
AS BEGIN

return @dtUtc AT TIME ZONE 'UTC' AT TIME ZONE @timezoneId

/* -- second way, faster

return SWITCHOFFSET(@dtUtc , DATENAME(tz, @dtUtc AT TIME ZONE @timezoneId))

*/

/* -- third way

declare @dtLocal datetimeoffset
set @dtLocal = @dtUtc AT TIME ZONE @timezoneId
return dateadd(minute, DATEPART (TZoffset, @dtLocal), @dtUtc)

*/

END
GO

但clr程序的工作速度快5倍:'-(

请注意,一个时区的偏移量可以更改为冬季时间或夏季时间。例如

select cast('2017-02-08 09:00:00.000' as datetime) AT TIME ZONE 'Eastern Standard Time'
select cast('2017-08-08 09:00:00.000' as datetime) AT TIME ZONE 'Eastern Standard Time'

结果:

2017-02-08 09:00:00.000 -05:00
2017-08-08 09:00:00.000 -04:00

你不能只是添加常数偏移量。

我没有发现任何这些示例有助于将日期时间存储为UTC到指定时区(不是服务器的时区,因为Azure SQL数据库以UTC运行)中的日期时间。我是这样处理的。它并不优雅,但它很简单,无需维护其他表就能给出正确答案:

select CONVERT(datetime, SWITCHOFFSET(dateTimeField, DATEPART(TZOFFSET, 
dateTimeField AT TIME ZONE 'Eastern Standard Time')))

告诉服务器保存时间的时间,'utc',然后要求它转换为特定的时区,在这种情况下是'巴西/东部'

quiz_step_progresses.created_at  at time zone 'utc' at time zone 'Brazil/East'

使用以下选择获取时区的完整列表;

select * from pg_timezone_names;

详情请点击这里。

https://popsql.com/learn-sql/postgresql/how-to-convert-utc-to-local-time-zone-in-postgresql

如果在数据库上启用CLR以及使用sql server的时区是一个选项,那么可以很容易地在. net中编写它。

public partial class UserDefinedFunctions
{
    [Microsoft.SqlServer.Server.SqlFunction]
    public static SqlDateTime fn_GetLocalFromUTC(SqlDateTime UTC)
    {
        if (UTC.IsNull)
            return UTC;

        return new SqlDateTime(UTC.Value.ToLocalTime());
    }
}

输入一个UTC日期时间值,然后输出相对于服务器的本地日期时间值。Null值返回Null。