I am using pq library in golang for postgres queries. I want to pass timestamp in the query string.
Ex. query = 'SELECT \* FROM table WHERE ts \<= NOW() - interval '5 seconds''
Instead of NOW() ...can I pass a timestamp?
Ex.
t=time.Now()
query = 'SELECT \* FROM table WHERE ts \<= t- interval '5 seconds''
I tried formatting the timestamp and using arguments to pass the timestamp but getting errors.
Related
I want to query postgres database table which has the column with timestamp in long milliseconds. But I have the time in date format "yyyy-MM-dd HH:mm:ssZ" like this. How can I convert this date format to long milliseconds to run the query?
You can either convert your long value to a proper timestamp:
select *
from the_table
where to_timestamp(the_millisecond_column / 1000) = timestamp '2020-10-05 07:42'
Or extract the seconds from the timestamp value :
select *
from the_table
where the_millisecond_column = extract(epoch from timestamp '2020-10-05 07:42') * 1000
The better solution is however to convert that column to a proper timestamp column to avoid the constant conversion between (milliseconds) and proper timestamp values
In the view I have a text column which contains a timestamp in this format '20/03/2018 00:00' and I'm trying to make a selection with a between clause but it's not working
SELECT id,entry_date
FROM v_view
WHERE entrada BETWEEN to_timestamp('20/03/2018 00:00','DD/MM/YYYY')::timestamp and to_timestamp('22/03/2018 00:00')::timestamp
order entry_date
with this error message
ERROR: el operador no existe: text >= timestamp without time zone
LINE 3: WHERE entry_date BETWEEN to_timestamp('20/03/2018 00:00','DD/MM.
you need to convert the entrada column value to a timestamp.
Also: casting the result of to_timestamp() to a timestamp is useless because to_timestamp() already returns a timestamp
SELECT id,entry_date
FROM v_view
WHERE to_timestamp(entrada, 'dd/mm/yyyy hh24:mi')
BETWEEN to_timestamp('20/03/2018', 'DD/MM/YYYY')
and to_timestamp('22/03/2018', 'dd/mm/yyyy')
order entry_date;
I prefer to use ANSI SQL timestamp literals over the to_timestamp function:
SELECT id,entry_date
FROM v_view
WHERE to_timestamp(entrada, 'dd/mm/yyyy hh24:mi')
BETWEEN timestamp '2018-03-20 00:00:00'
and timestamp '2018-03-22 00:00:00'
order entry_date
Do not store date, time or timestamp values in a text or varchar column. You should define that column as timestamp then you don't need to convert anything and you don't need to deal with invalid timestamp values in that column.
I am trying to retrieve time difference in minutes from a table(login_history as t1) using postgresql .
When i tried this code
((date_part('hour', timestamp '2014-04-25 09:44:21')- date_part('hour', timestamp '2014-04-25 08:32:21'))*60 +(date_part('minutes', timestamp '2014-04-25 09:44:21')- date_part('minutes', timestamp '2014-04-25 08:32:21'))) as TimeNew
It works fine.
But when i tried to retrieve information from a table t1 using this code
((date_part('hour', timestamp t1.login_date)- date_part('hour', timestamp t1.logout_date))*60 +
(date_part('minutes', timestamp t1.login_date)- date_part('minutes', timestamp t1.logout_date))
) as TimeNew
It throws this error
SQLSTATE[42601]: Syntax error: 7 ERROR: syntax error at or near "t1"
Thanks
I would use the interval that results from subtracting two timestamps for a much simpler expression:
select extract (epoch from (timestamp '2014-04-25 09:44:21' - timestamp '2014-04-25 08:32:21'))::integer/60
(gives 72)
or for your table:
select extract (epoch from (t1.logout_date - t1.login_date))::integer/60
If you need to cast:
select extract (epoch from (t1.logout_date::timestamp - t1.login_date::timestamp))::integer/60
or see the to_timestamp function for custom string parsing: http://www.postgresql.org/docs/9.4/static/functions-formatting.html
I needed to remove the timestamp from the query before t1 and the query works.
My first query is:
SELECT distinct wfc_request_job_id,wfc_request_job_info,
replace(iso_cc,';',' ') as "iso_cc",to_char(wfc_request_start_ts,'yyyy-MM-dd HH:mm:ss') as ts,
sent_message_count,
(link_object_count + poi_object_count + point_address_object_count) as request_object_count
FROM wfc_request_job
where
wfc_request_job_id=173526;
This returns ts as 2015-08-16 03:08:59
Second Query:
SELECT wfc_request_job_id,wfc_request_start_ts,wfc_request_end_ts,replace(iso_cc,';',' ') as "iso_ccs",sent_message_count,wfc_queue_name
FROM wfc_request_job
where
to_char(wfc_request_start_ts,'YYYY-MM-DD') >= to_char(to_date('08/16/2015','MM/DD/YYYY'),'YYYY-MM-DD')
and to_char(wfc_request_start_ts,'YYYY-MM-DD') <= to_char(to_date('08/16/2015','MM/DD/YYYY'),'YYYY-MM-DD')
order by wfc_request_job_id desc
This returns ts of the job id mentioned above as - "2015-08-16 15:58:59.809+02"
How can I make both the queries return ts in UTC+02 - i.e. same timezone
The data type of wfc_request_start_ts is - timestamp with timezone
I changed to queries to have the format HH24:MI:SS however that did not help. Please note that the webapp using these queries will be opened in both Germany and USA.
According to postgresql manual to_char there is TZ (and OF as of v9.4) template patterns for Date/Time formatting.
Therefore in query you need to add it so
postgres=# select to_char(now(),'yyyy-MM-dd HH24:mm:ss TZ');
to_char
------------------------
2015-08-19 12:08:56 CEST
(1 row)
Also, make sure you specify timezone when converting
so instead
to_date('08/16/2015','MM/DD/YYYY')
use
TIMESTAMP WITH TIME ZONE '2015-08-16 00:00:00+02';
in second query.
I have a relation that maintains monthly historical data. This data is added to the table on the last day of each month. A service I am writing can then be called specifying a month and a number of months prior for which to retrieve the historical data. I am doing this by creating startDate and endDate variables, and then returning data between the two. The problem I am having is that startDate is a variable number of months before endDate, and I cannot figure out how to use a variable period in an interval.
Here is what I have:
DECLARE
endDate TIMESTAMP := (DATE_TRUNC('MONTH',$2) + INTERVAL '1 MONTH') - INTERVAL '1 DAY';
startDate TIMESTAMP := endDate - INTERVAL $3 'MONTH';
I know that the line for startDate is not correct. How is this properly done?
Use this line:
startDate TIMESTAMP := endDate - ($3 || ' MONTH')::INTERVAL;
and note the space before MONTH.
Basically: You construct a string with like 4 MONTH and cast it with ::type into a proper interval.
Edit: I' have found another solution: You can calculate with interval like this:
startDate TIMESTAMP := endDate - $3 * INTERVAL '1 MONTH';
This looks a little bit nicer to me.
This code has nothing directly to do with your situation, but it does illustrate how to use variables in INTERVAL arithmetic. My table's name is "calendar".
CREATE OR REPLACE FUNCTION test_param(num_months integer)
RETURNS SETOF calendar AS
$BODY$
select * from calendar
where cal_date <= '2008-12-31 00:00:00'
and cal_date > date '2008-12-31' - ($1 || ' month')::interval;
$BODY$
LANGUAGE sql VOLATILE
COST 100
ROWS 1000;
The most readable way I have found to pass a variable time period to Postgres is similar to A.H.'s answer: by multiplying by an integer. But this can be done without a cast.
Python example (with sqlalchemy and pandas):
import pandas as pd
import sqlalchemy as sa
connection = sa.create_engine(connection_string)
df = pd.read_sql(
sa.text('''
select * from events
where
event_date between now() - (interval '1 day' * :ndays) and now()
limit 100;
'''),
connection,
params={'ndays': 100}
)
The number of days (ndays) is passed as an integer from within Python - so unintended consequences are less likely.
My approach is like this.. It gives me option to set specific date or a relative range.
create or replace function search_data(_time_from timestamptz default null, _last_interval text default null)
returns setof journal
language plpgsql as
$$
begin
return query
select *
from journal
where created >= case
when _time_from is not null
then _time_from
else now() - _last_interval::interval end;
end;
$$;
While the above accepted answer is fine, it's a little bit antiquated - requiring a bit more mental energy to read than needed if you're running on Postgres 9.4+.
Old Way (Postgres Versions < 9.4)
startDate TIMESTAMP := endDate - $3 * INTERVAL '1 MONTH';
New Way (Postgres 9.4+)
startDate TIMESTAMP := endDate - MAKE_INTERVAL(MONTHS => $3);
If you are on Postgres 9.4+, the new MAKE_INTERVAL() function seems much more readable - probably why they created it.
If you want something you can run in your editor, here are a couple of
examples (I substituted the original variable binding $3 with the number 2 for an example of 2-months prior to the current date).
SELECT CURRENT_DATE - 2 * INTERVAL '1 MONTH';
SELECT CURRENT_DATE - MAKE_INTERVAL(MONTHS => 2);