I have a PostgreSQL timestamp as
2009-12-22 11:01:46
I need to change this to date as
2009-12-22
So that I can compare the dates in postgreSQL
How can I achieve this transformation?
Cast it to date.
SELECT yourtimestamp::date;
If you need to extract other kinds of stuff, you might want to use EXTRACT or date_trunc
Both links are to the same page, were you'll find more date/time-related functions.
You can either use one of the Postgres date functions, such as date_trunc, or you could just cast it, like this:
SELECT timestamp '2009-12-22 11:01:46'::date
>>> 2009-12-22
SELECT [timestamp column] ::date;
Along in select query you can search on the basis of date
WHERE [timestamp column] :: date = '2022-05-30'
Related
I am newbie to KDB. I have a KDB table which I am querying as:
select[100] from table_name
now this table has got some date columns which have dates stored in this format
yyyy.mm.dd
I wish to query that table and retrieve the date fields in specific format (like mm/dd/yyyy). If this would've been any other RDBMS table this is what i would have done:
select to_date(date_field,'mm/dd/yyyy') from table_name
I need kdb equivalent of above. I've tried my best to go through the kdb docs but unable to find any function / example / syntax to do that.
Thanks in advance!
As Anton said KDB doesn't have an inbuilt way to specify the date format. However you can extract the components of the date individually and rearrange as you wish.
For the example table t with date column:
q)t
date
----------
2008.02.04
2015.01.02
q)update o:{"0"^"/"sv'flip -2 -2 4$'string`mm`dd`year$\:x}date from t
date o
-----------------------
2008.02.04 "02/04/2008"
2015.01.02 "01/02/2015"
From right to left inside the function: we extract the month,day and year components with `mm`dd`year$:x before stringing the result. We then pad the month and day components with a null character (-2 -2 4$') before each and add the "/" formatting ("/"sv'flip). Finally the leading nulls are filled with "0" ("0"^).
Check out this GitHub library for datetime formatting. It supports the excel way of formatting date and time. Though it might not be the right fit for formatting a very large number of objects (but if distinct dates are very less then a keyed table and lj can be used for lookup).
q).dtf.format["mm/dd/yyyy"; 2016.09.23]
"09/23/2016"
q).dtf.format["dd mmmm yyyy"; 2016.09.03] // another example
"03 September 2016"
I don't think KDB has built-in date formatting features.
The most reliable way is to format date by yourself.
For example
t: ([]date: 10?.z.d);
update dateFormatted: {x: "." vs x; x[1],"/",x[2],"/",x[0]} each string date from t
gives
date dateFormatted
------------------------
2012.07.21 "07/21/2012"
2001.05.11 "05/11/2001"
2008.04.25 "04/25/2008"
....
Or, more efficient way to do the same formatting is
update dateFormatted: "/"sv/:("."vs/:string date)[;1 2 0] from t
now qdate is available for datetime parsing and conversion
I have dates in a postgres database. The problem is they are stored in a string field and have values similar to: "1187222400000" (which would correspond to 07.08.2007).
I would like to convert them into readable dates usind some SQL to_date() expression or something similar but can't come up with the correct syntax to make it work.
There really isn't enough information here for a conclusion, so I propose this 'scientific-wild-ass-guess' to resolve your puzzle. :)
It appears this number is UNIX 'epoch time' in milliseconds. I'll show this example as if your string field had the arbitrary name, 'epoch_milli'. In postgresql you can convert it to a time stamp using this statement:
SELECT TIMESTAMP WITH TIME ZONE 'epoch' + epoch_milli * INTERVAL '1 millisecond';
or using this built-in postgresql function:
SELECT to_timestamp(epoch_milli / 1000)
either of which, for the example '1187222400000', produces the result
"2007-08-15 17:00:00-07"
You can do some of your own sleuthing with quite a few values selected similarly to this:
SELECT to_timestamp(epoch_milli/1000)::DATE
FROM (VALUES (1187222400000),(1194122400000)) AS val(epoch_milli);
"Well, bollocks, man. I just want the date." Point taken.
Simply cast the timestamp to a date to discard the excess bits:
SELECT to_timestamp(epoch_milli / 1000)::DATE
Of course its possible that this value is a conversion or is relative to some other value, hence the request for a second example data point.
I'm new to PostgreSQL and I have the following question:
I have a table with just an id-column and a data-column, which uses the jsonb-type. Inside the jsonb-object I have a datetime field. I read in various posts, that I should use the ISO-8601 dateformat to store in the DB.
I want to filter my table by date like this:
SELECT * FROM table WHERE data->'date' > '2016-01-01T00:00'
Is this really the best date-format for this purpose?
Thanks in advance :)
IMHO Your query should produce
ERROR: operator does not exist: jsonb > timestamp with time zone
If I get it right. In case you change -> to ->> it should get a text value instead of jsonb field (which is also not comparable to timestamp).
It should be smth like
SELECT * FROM table WHERE (data->>'date')::timestamptz > '2016-01-01T00:00' to work
The big advantage of that format is that string order corresponds to date order, so a comparison like the one you quote in your question would actually work as intended.
A second advantage is that a timestamp in that format can easily be converted to a PostgreSQL timestamp with time zone value, because the type input function understands this format.
I hope you are not dealing with dates “before Christ”, because it wouldn't work so easily with those.
I am building a map in CartoDB which uses Postgres. I'm simply trying to display my dates as: 10-16-2014 but, haven't been able to because Postgres includes an unneeded timestamp in every date column.
Should I alter the column to remove the timestamp or, is it simply a matter of a (correct) SELECT query? I can SELECT records from a date range no problem with:
SELECT * FROM mytable
WHERE myTableDate >= '2014-01-01' AND myTableDate < '2014-12-31'
However, my dates appear in my CartoDB maps as: 2014-10-16T00:00:00Z and I'm just trying to get the popups on my maps to read: 10-16-2014.
Any help would be appreciated - Thank you!
You are confusing storage with display.
Store a timestamp or date, depending on whethether you need time or not.
If you want formatted output, ask the database for formatted output with to_char, e.g.
SELECT col1, col2, to_char(col3, 'DD-MM-YY'), ... FROM ...;
See the PostgreSQL manual.
There is no way to set a user-specified date output format. Dates are always output in ISO format. If PostgreSQL let you specify other formats without changing the SQL query text it'd really confuse client drivers and applications that expect the date format the protocol specifies and get something entirely different.
You have two basic options.
1 Change the column from a timestamp to a date column.
2 Cast to date in your SQL query (i.e. mytimestamp::date works).
In general if this is a presentation issue, I don't usually think that is a good reason to muck around with the database structure. That's better handled by client-side processing or casting in an SQL query. On the other hand if the issue is a semantic one, then you may want to revisit your database structure.
Please pardon my ignorance if I have missed any documentation/solution for the same. But I searched the web and could not find an answer.
I have a simple question. In the DB2 table,I have a column of type date and the with data of format 04/25/2013 12:00:00AM . When I query the DB2 database, I want to obtain just the date and not the timestamp i.e to obtain "04/25/2013" and not "04/25/2013 12:00:00AM". I tried DATE(column name) and just gave back the complete value including the time stamp.
This looks like a TIMESTAMP and not a DATE column. If it is indeed a TIMESTAMP column try this:
select varchar_format(current timestamp, 'MM/DD/YYYY') from sysibm.sysdummy1 ;
Just replace the current timestamp in the above example with your column and sysibm.sysdummy1 with your table.
The good thing about varchar_format is that it lets you easily format the timestamp. Just change the 'MM/DD/YYYY' part to 'YYYY.MM.DD' to get a format like '2017.08.18'.