[英]Converting timestamp field to proper time zone
我们的数据存储在UTC + 00:00时区。
要进行查询,我们必须将时间戳输入从“欧洲/巴黎”时区转换为UTC + 00:00,即欧洲/伦敦。 当我们获得这些数据时,将输出时间戳转换为“欧洲/巴黎”时区。
因此,我发现的解决方案是cast(VALIDATIONTIME as timestamp) at time zone 'Europe/Paris'
时区使用诸如cast(VALIDATIONTIME as timestamp) at time zone 'Europe/Paris'
类的“在时区” cast(VALIDATIONTIME as timestamp) at time zone 'Europe/Paris'
它适用于输入,但不适用于输出(当我们获得数据时)。
那么如何使其适用于输入和输出呢?
例:
Orders table
ID VALIDATIONTIME
9986 14/03/16 09:47:29,823000000
6764 20/03/16 12:07:39,453000000
要获取行ID 9986,查询将是:
select cast(VALIDATIONTIME as timestamp) at time zone 'Europe/Paris' as validation
from orders
where VALIDATIONTIME between cast(TO_TIMESTAMP('14/03/2016 10:45:18', 'DD/MM/YYYY HH24:MI:SS') as timestamp) at time zone 'UTC'
and cast(TO_TIMESTAMP('14/03/2016 10:50:18', 'DD/MM/YYYY HH24:MI:SS') as timestamp) at time zone 'UTC';
但是输出(验证)没有改变!
at time zone
语法会将带有时区值的时间戳从当前时区转换为您指定的时间戳。 当您将其应用于没有时区的普通时间戳时,正如您跟随cast()
,首先会隐式转换为会话时区。
我认为您确实在寻找from_tz()
函数 :
select VALIDATIONTIME at time zone 'Europe/Paris' as validation
from orders
where VALIDATIONTIME between
FROM_TZ(TO_TIMESTAMP('14/03/2016 10:45:18', 'DD/MM/YYYY HH24:MI:SS'), 'Europe/Paris')
and
FROM_TZ(TO_TIMESTAMP('14/03/2016 10:50:18', 'DD/MM/YYYY HH24:MI:SS'), 'Europe/Paris');
您可以通过独立查询查看生成的时间; 这还将指定的巴黎时区中的时间转换为UTC进行比较:
select
FROM_TZ(TO_TIMESTAMP('14/03/2016 10:45:18', 'DD/MM/YYYY HH24:MI:SS'), 'Europe/Paris')
as Paris,
FROM_TZ(TO_TIMESTAMP('14/03/2016 10:45:18', 'DD/MM/YYYY HH24:MI:SS'), 'Europe/Paris')
at time zone 'UTC' as London
from dual;
PARIS LONDON
------------------------------------------ ------------------------------------------
14-MAR-16 10.45.18.000000000 EUROPE/PARIS 14-MAR-16 09.45.18.000000000 UTC
(当然,夏天夏天伦敦不是UTC,但现在我们将忽略该细节;我假设您实际上是要使用UTC,而不是伦敦)。
您可能必须根据其数据类型和会话时区validationtime
更多地操作validationtime
时间。 通过简单的数据设置和validationtime
作为普通时间戳(无时区信息):
create table orders (id number, validationtime timestamp);
insert into orders (id, validationtime)
values (9986, to_timestamp('14/03/16 09:47:29,823000000', 'DD/MM/RR HH24:MI:SS,FF'));
insert into orders (id, validationtime)
values (6764, to_timestamp('20/03/16 12:07:39,453000000', 'DD/MM/RR HH24:MI:SS,FF'));
如果我的会议是在伦敦时间,则基本查询有效:
alter session set time_zone = 'Europe/London';
select VALIDATIONTIME at time zone 'Europe/Paris' as validation
from orders
where VALIDATIONTIME between
FROM_TZ(TO_TIMESTAMP('14/03/2016 10:45:18', 'DD/MM/YYYY HH24:MI:SS'), 'Europe/Paris')
and
FROM_TZ(TO_TIMESTAMP('14/03/2016 10:50:18', 'DD/MM/YYYY HH24:MI:SS'), 'Europe/Paris');
VALIDATION
------------------------------------------
14-MAR-16 10.47.29.823000000 EUROPE/PARIS
但是,如果我将会话时区更改为巴黎,那么现在不会:
alter session set time_zone = 'Europe/Paris';
select VALIDATIONTIME at time zone 'Europe/Paris' as validation
from orders
where VALIDATIONTIME between
FROM_TZ(TO_TIMESTAMP('14/03/2016 10:45:18', 'DD/MM/YYYY HH24:MI:SS'), 'Europe/Paris')
and
FROM_TZ(TO_TIMESTAMP('14/03/2016 10:50:18', 'DD/MM/YYYY HH24:MI:SS'), 'Europe/Paris');
no rows selected
因此,您需要将表中的原始时间戳记指定为UTC,您可以使用相同的功能执行此操作:
select FROM_TZ(VALIDATIONTIME, 'UTC') at time zone 'Europe/Paris' as validation
from orders
where FROM_TZ(VALIDATIONTIME, 'UTC') between
FROM_TZ(TO_TIMESTAMP('14/03/2016 10:45:18', 'DD/MM/YYYY HH24:MI:SS'), 'Europe/Paris')
and
FROM_TZ(TO_TIMESTAMP('14/03/2016 10:50:18', 'DD/MM/YYYY HH24:MI:SS'), 'Europe/Paris');
VALIDATION
------------------------------------------
14-MAR-16 10.47.29.823000000 EUROPE/PARIS
本质上,在比较之前,您需要确保所使用的所有日期都在同一区域中。 另一种方法是将可变日期强制为UTC,然后强制为普通时间戳:
select FROM_TZ(VALIDATIONTIME, 'UTC') at time zone 'Europe/Paris' as validation
from orders
where VALIDATIONTIME
between
cast(FROM_TZ(TO_TIMESTAMP('14/03/2016 10:45:18', 'DD/MM/YYYY HH24:MI:SS'),
'Europe/Paris') at time zone 'UTC' as timestamp)
and
cast(FROM_TZ(TO_TIMESTAMP('14/03/2016 10:50:18', 'DD/MM/YYYY HH24:MI:SS'),
'Europe/Paris') at time zone 'UTC' as timestamp);
VALIDATION
------------------------------------------
14-MAR-16 10.47.29.823000000 EUROPE/PARIS
...看起来更复杂,但是由于它不会修改where
子句中的table列,因此它将允许该列上的任何索引继续使用。
在这里,变量字符串将转换为纯时间戳,声明为位于巴黎时区,转换为UTC,然后转换回纯时间戳-因此,其格式与表列数据的格式和(隐含)时区相同。
Oracle安装程序 :
CREATE TABLE orders (
ID INT,
VALIDATIONTIME TIMESTAMP
);
INSERT INTO orders VALUES (
9968,
FROM_TZ( TIMESTAMP '2016-03-14 09:47:29.823', 'Europe/Paris' )
AT TIME ZONE 'UTC'
);
-- Alternate syntax for inserting from TZ:
INSERT INTO orders VALUES (
6764,
TO_TIMESTAMP_TZ( '2016-03-20 20:07:39.453 Europe/Paris',
'YYYY-MM-DD HH24:MI:SS.FF TZR' )
AT TIME ZONE 'UTC'
);
甚至更简单:
INSERT INTO orders VALUES (
9968,
TIMESTAMP '2016-03-14 09:47:29.823+01:00' AT TIME ZONE 'UTC'
);
要么:
INSERT INTO orders VALUES (
6764,
TIMESTAMP '2016-03-20 20:07:39.453 Europe/Paris' AT TIME ZONE 'UTC'
);
查询1 :
SELECT * FROM orders;
ID VALIDATIONTIME
---- -----------------------------
9986 2016-03-14 08:47:29.823000000
6764 2016-03-20 19:07:39.453000000
(这在表中显示了UTC时间)
查询2 :
SELECT id,
CAST( VALIDATIONTIME AS TIMESTAMP WITH TIME ZONE )
AT TIME ZONE 'Europe/Paris' AS validationtime
FROM orders
ID VALIDATIONTIME
---- ------------------------------------------
9986 2016-03-14 09:47:29.823000000 EUROPE/PARIS
6764 2016-03-20 20:07:39.453000000 EUROPE/PARIS
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