Question

我们的数据存储在UTC + 00:00的时区。

要进行一些查询，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。当我们获得此数据时，将输出时间戳转换为“欧洲/巴黎”时区。

所以我找到的解决方案是使用像cast(VALIDATIONTIME as timestamp) at time zone 'Europe/Paris'这样的“在时区” 它适用于输入，但不适用于输出（当我们获取数据时）。

那么如何使它适用于输入和输出？

示例：

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，查询将为：

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';

但输出（验证）不会改变!!

Answer 1

at time zone syntax将带有时区值的时间戳从其当前区域转换为您指定的时区。当您将其应用于没有时区的普通时间戳时，当您跟随cast()时，会先隐式转换为会话时区。

我认为你真的在寻找the from_tz() function：

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;这也将指定为巴黎时区的时间转换为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，伦敦在夏天不是UTC，但我们暂时忽略这个细节;我假设你真的想要UTC而不是伦敦。）

您可能需要根据其数据类型和会话时区操作validationtime。使用一些简单的数据设置和validationtime作为普通时间戳（没有时区信息）：

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'));

如果我的会话在伦敦时间，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，那么它现在不会：

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，您需要在表格中指定UTC的原始时间戳，您可以使用相同的函数执行此操作：

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

基本上，在比较它们之前，您需要确保所使用的所有日期都在同一区域中。另一种方法是将变量日期强制为UTC，然后强制为简单时间戳：

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，但由于它不修改where子句中的表列，它将允许仍然使用该列上的任何索引。

此处变量字符串被转换为普通时间戳，声明为在巴黎时区，转换为UTC，然后转换回普通时间戳 - 因此它的格式与（隐含）时区相同表列数据。

Answer 2

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'
);

或：

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

（这表示表中的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

将时间戳字段转换为适当的时区

2 个答案: