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
你可以在SQL Server 2008或更高版本上这样做:
SELECT CONVERT(datetime,
SWITCHOFFSET(CONVERT(datetimeoffset,
MyTable.UtcColumn),
DATENAME(TzOffset, SYSDATETIMEOFFSET())))
AS ColumnInLocalTime
FROM MyTable
你也可以用更简洁的方法:
SELECT DATEADD(mi, DATEDIFF(mi, GETUTCDATE(), GETDATE()), MyTable.UtcColumn)
AS ColumnInLocalTime
FROM MyTable
无论您做什么,都不要使用-来减去日期,因为该操作不是原子的,并且由于在不同时间(即非原子地)检查的系统datetime和本地datetime之间的竞争条件,您有时会得到不确定的结果。
请注意,这个答案没有考虑夏令时。如果你想包含夏令时调整,也请参阅以下SO问题:
如何在SQL Server中创建夏令时开始和结束函数
其他回答
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。
您必须重新格式化字符串以及转换为正确的时间。在这种情况下,我需要祖鲁时间。
Declare @Date datetime;
Declare @DateString varchar(50);
set @Date = GETDATE();
declare @ZuluTime datetime;
Declare @DateFrom varchar (50);
Declare @DateTo varchar (50);
set @ZuluTime = DATEADD(second, DATEDIFF(second, GETDATE(), GETUTCDATE()), @Date);
set @DateString = FORMAT(@ZuluTime, 'yyyy-MM-ddThh:mm:ssZ', 'en-US' )
select @DateString;
对甲骨文来说最好的方法:
硬编码的datetime:
SELECT TO_CHAR(CAST((FROM_TZ(CAST(TO_DATE('2018-10-27 21:00', 'YYYY-MM-DD HH24:MI') AS TIMESTAMP), 'UTC') AT TIME ZONE 'EET') AS DATE), 'YYYY-MM-DD HH24:MI') UTC_TO_EET FROM DUAL
结果: 2018-10-28 00:00
列名和表名:
SELECT TO_CHAR(CAST((FROM_TZ(CAST(COLUMN_NAME AS TIMESTAMP), 'UTC') AT TIME ZONE 'EET') AS DATE), 'YYYY-MM-DD HH24:MI') UTC_TO_EET FROM TABLE_NAME
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')))
这可以在没有函数的情况下完成。下面的代码将把UTC时间转换为考虑夏令时的山地时间。相应地调整所有的-6和-7数字到您的时区(即对于EST,您将分别调整为-4和-5)
--Adjust a UTC value, in the example the UTC field is identified as UTC.Field, to account for daylight savings time when converting out of UTC to Mountain time.
CASE
--When it's between March and November, it is summer time which is -6 from UTC
WHEN MONTH ( UTC.Field ) > 3 AND MONTH ( UTC.Field ) < 11
THEN DATEADD ( HOUR , -6 , UTC.Field )
--When its March and the day is greater than the 14, you know it's summer (-6)
WHEN MONTH ( UTC.Field ) = 3
AND DATEPART ( DAY , UTC.Field ) >= 14
THEN
--However, if UTC is before 9am on that Sunday, then it's before 2am Mountain which means it's still Winter daylight time.
CASE
WHEN DATEPART ( WEEKDAY , UTC.Field ) = 1
AND UTC.Field < '9:00'
--Before 2am mountain time so it's winter, -7 hours for Winter daylight time
THEN DATEADD ( HOUR , -7 , UTC.Field )
--Otherwise -6 because it'll be after 2am making it Summer daylight time
ELSE DATEADD ( HOUR , -6 , UTC.Field )
END
WHEN MONTH ( UTC.Field ) = 3
AND ( DATEPART ( WEEKDAY , UTC.Field ) + 7 ) <= DATEPART ( day , UTC.Field )
THEN
--According to the date, it's moved onto Summer daylight, but we need to account for the hours leading up to 2am if it's Sunday
CASE
WHEN DATEPART ( WEEKDAY , UTC.Field ) = 1
AND UTC.Field < '9:00'
--Before 9am UTC is before 2am Mountain so it's winter Daylight, -7 hours
THEN DATEADD ( HOUR , -7 , UTC.Field )
--Otherwise, it's summer daylight, -6 hours
ELSE DATEADD ( HOUR , -6 , UTC.Field )
END
--When it's November and the weekday is greater than the calendar date, it's still Summer so -6 from the time
WHEN MONTH ( UTC.Field ) = 11
AND DATEPART ( WEEKDAY , UTC.Field ) > DATEPART ( DAY , UTC.Field )
THEN DATEADD ( HOUR , -6 , UTC.Field )
WHEN MONTH ( UTC.Field ) = 11
AND DATEPART ( WEEKDAY , UTC.Field ) <= DATEPART ( DAY , UTC.Field )
--If the weekday is less than or equal to the calendar day it's Winter daylight but we need to account for the hours leading up to 2am.
CASE
WHEN DATEPART ( WEEKDAY , UTC.Field ) = 1
AND UTC.Field < '8:00'
--If it's before 8am UTC and it's Sunday in the logic outlined, then it's still Summer daylight, -6 hours
THEN DATEADD ( HOUR , -6 , UTC.Field )
--Otherwise, adjust for Winter daylight at -7
ELSE DATEADD ( HOUR , -7 , UTC.Field )
END
--If the date doesn't fall into any of the above logic, it's Winter daylight, -7
ELSE
DATEADD ( HOUR , -7 , UTC.Field )
END
推荐文章
- 如何在Ruby On Rails中使用NuoDB手动执行SQL命令
- 查询JSON类型内的数组元素
- 确定记录是否存在的最快方法
- 获得PostgreSQL数据库中当前连接数的正确查询
- 在SQL选择语句Order By 1的目的是什么?
- 从现有模式生成表关系图(SQL Server)
- 我如何循环通过一组记录在SQL Server?
- 数据库和模式的区别
- 如何在SQL Server中一次更改多个列
- 如何从命令行通过mysql运行一个查询?
- 外键约束可能导致循环或多条级联路径?
- 使用LIMIT/OFFSET运行查询,还可以获得总行数
- 当恢复sql时,psql无效命令\N
- 货币应该使用哪种数据类型?
- 如何选择每一行的列值不是独特的