I have an external table (from GCS) in bigquery that by auto scheme detect a datetime column and creates a timestamp column in the table with UTC. The time zone of my data is Central (America/Chicago).
I know that the timezone is central and I want to create another column with UTC timezone. I tried using parse_timestamp/converting to string then to datetime with timezone. But couldn't get it right. Any suggestion?
The following query will output the correct UTC time. Remember that BigQuery stores timestamps in UTC.
with sample as (
select timestamp('2021-01-10 08:00:00', 'UTC') as ts
)
select timestamp(datetime(ts), 'America/Chicago') from sample;
Related
I have a Java application that inserts data into a database using prepared statements. In the preparedStamement date is set in UTC format.
preparedStatement.setDate(index, new java.sql.Date(date.getTime()), UTC);
I want to be sure that when read and write operations execute on the table, the response should ALWAYS be in UTC format. At the below query, when the data is read it will be converted to the client's timezone. I don't want TIME_COLUMN to be converted to any time zone. It should remain in the UTC time zone. How can I define TIME_COLUMN in that way?
Notes: I cannot edit the DB timezone. I cannot edit select queries using At time zone.
"TIME_COLUMN" TIMESTAMPTZ default (now() at time zone 'utc'),
You could set the timezone of your RDBMS to UTC, see https://medium.com/building-the-system/how-to-store-dates-and-times-in-postgresql-269bda8d6403
When that's done, whatever dates you store, they will be in UTC. Converting from UTC into something else can be done either in queries, like
select created_at at time zone 'utc' at time zone 'america/los_angeles'
from users;
Taken from https://popsql.com/learn-sql/postgresql/how-to-convert-utc-to-local-time-zone-in-postgresql
Or, you can convert the timezone at application level.
I want to create a table in redshift that stores incrementally incoming data from the source. The date field in the mysql source is not stored as UTC. Is it possible to convert and store the new record as UTC upon record creation.
I was thinking doing something like that:
CREATE TABLE test(
my_dt_field datetime without timezone NOT NULL ...)
Any help would be very appreciated!
Redshift provides following options of datatypes available to store dates:
1.DATE
Use the DATE data type to store simple calendar dates without time stamps.
2.TIMESTAMP
TIMESTAMP is an alias of TIMESTAMP WITHOUT TIME ZONE.
Use the TIMESTAMP data type to store complete timestamp values that include the date and the time of day.
TIMESTAMP columns store values with up to a maximum of 6 digits of precision for fractional seconds.
If you insert a date into a TIMESTAMP column, or a date with a partial time stamp value, the value is implicitly converted into a full time stamp value with default values (00) for missing hours, minutes, and seconds. Time zone values in input strings are ignored.
By default, TIMESTAMP values are Coordinated Universal Time (UTC) in both user tables and Amazon Redshift system tables.
3.TIMESTAMPTZ
TIMESTAMPTZ is an alias of TIMESTAMP WITH TIME ZONE.
Use the TIMESTAMPTZ data type to input complete time stamp values that include the date, the time of day, and a time zone. When an input value includes a time zone, Amazon Redshift uses the time zone to convert the value to Coordinated Universal Time (UTC) and stores the UTC value.
To view a list of supported time zone names, execute the following command.
select pg_timezone_names();
To answer your question declare your column datatype as TIMESTAMP, by default it stores in UTC
You can also refer AWS document here: https://docs.aws.amazon.com/redshift/latest/dg/r_Datetime_types.html
When I do a SELECT statement that outputs a TIMESTAMP WITH TIME ZONE column, it doesn't include the time zone in the output. It just outputs the date and time without the timezone, after converting it to my local timezone.
I have 2 questions:
How to get all TIMESTAMP WITH TIME ZONE columns to always display their time zones in the output, rather than the default of omitting it?
How to get all TIMESTAMP WITH TIME ZONE columns to output with a default time zone of UTC? I know there's ways to do this on a per-query basis, but I'd like to do it in every case with needing to modify any queries. So a server setting maybe?
for one column:
SELECT colname AT TIME ZONE 'UTC' FROM tablename;
for all
SET TIMEZONE TO 'UTC';
see also ALTER ... SET ...
I have a SQL Builder library that direcltly uses ADO.NET. I have a means of creating a select query with a greater-than-or-equal operator, like:
select *
from book
where book.date_created >= {some date}
My issue is that {some date} is going to always be in the UTC time zone, but it's being compared to the book.date_created column which is a TIMESTAMP(6) WITH TIME ZONE column, which will not be in the UTC timezone.
I can execute the query, but my results are off becuaes of timezone comparisons. My query is for all books where the date_created >= x, but some of the results returned are not greater than x because after subtracting 5 hours for the time zone, they are now less than x. The IDataRecord DateTime fields returned are converted to UTC using DateTime.SpecifyKind()
Can I form my query such that it interprets book.date_created in the UTC timezone?
Note: While I'd love to change my Oracle DB columns to not specify timezones, changing table structures is not something I can do.
Edit:
Currently, {some date} is a SQL Parameter. It's backing datatype is a DateTime with UTC as the timezone. As a parameter, it is a TimestampWithTZ. The Value of the parameter is a DateTime with the kind specified as UTC as well.
Update:
The issue seems to be related to my results set from the IDataRecord. When I pull DateTimes off, I use DateTime.SpecifyKind() to put them in UTC mode. The problem is, the date times come out as DateTimeKind.Unspecified. When converting from Unspecified to UTC, it just drops the timezone and declares it is UTC without changing the underlying value. I'm not sure how to have the IDataRecord pull in the TimeZone value.
You need to use the FROM_TZ function that transforms a TIMESTAMP into a TIMESTAMP WITH TIME ZONE. For example, if you know that your variable is in UTC time (+0:00):
SELECT *
FROM book
WHERE date_created >= from_tz(<timestamp>, '+0:00');
Here's a sample script that shows the behaviour you describe (your local time zone should be set to +1:00):
CREATE TABLE t (tz TIMESTAMP(6) WITH TIME ZONE);
INSERT INTO t VALUES
(to_timestamp_tz('20000101 00:00:00 +1:00','yyyymmdd hh24:mi:ss tzh:tzm'));
INSERT INTO t VALUES
(to_timestamp_tz('20000101 00:00:00 -1:00','yyyymmdd hh24:mi:ss tzh:tzm'));
-- This will return two values instead of one
SELECT *
FROM t
WHERE tz >= to_timestamp('20000101 00:00:00', 'yyyymmdd hh24:mi:ss');
-- This query will return only one row
SELECT *
FROM t
WHERE tz >= from_tz (to_timestamp('20000101 00:00:00',
'yyyymmdd hh24:mi:ss'), '+0:00');
below links will help you.
Datetime Datatypes and Time Zone Support
TIMESTAMP WITH TIME ZONE Data Type
Write Time Zone Aware Code in Oracle
ORACLE timezone summary
Oracle Date and Time data types
I am having a problem from my database.
I never been used to work in PostgreSQL, and i would like to make a select from a UTC datetime field and getting a GMT Datetime as result.
Actually my request is : select dateheure from position
What should be the Postgresql request to do what i want to do ???
Thanks a lot
Gwenael
PostgreSQL does have two datetime types:
timestamp without time zone (default implicit timestamp)
timestamp with time zone
I guess that you have table with UTC datetime (without time zone type):
CREATE TEMP TABLE datetimetest
(
datetime timestamp
);
\d datetimetest
Table "pg_temp_1.datetimetest"
Column | Type | Modifiers
----------+-----------------------------+-----------
datetime | timestamp without time zone |
INSERT INTO datetimetest SELECT CURRENT_TIMESTAMP AT TIME ZONE 'UTC';
SELECT datetime FROM datetimetest;
datetime
----------------------------
2011-08-15 15:04:06.507166
(1 row)
To get datetime in some timezone you could use AT TIME ZONE construct:
SET TIME ZONE 'UTC';
SELECT datetime AT TIME ZONE 'GMT-5' FROM datetimetest;
timezone
-------------------------------
2011-08-15 10:04:06.507166+00
(1 row)
In a different post I use a CHECK() constraint to make sure that you only store and receive UTC out of the database. Hopefully it's helpful.