date column's format : '2017-03-17'
SELECT EXTRACT(MONTH FROM DATE '2017-03-17') FROM table;
It's giving me 3 instead of March.
extract() returns a number. You want a string, so you can use to_char(<col>, 'Mon'):
select to_char(now(), 'MON')
or for mixed case:
select to_char(now(), 'Mon')
Related
I have a list of dates each with a value in Postgresql.
For each date I want to sum the value for this date and the previous 4 days.
I also want to sum the values for the start of that month to the present date. So for example:
For 07/02/2021 sum all values from 07/02/2021 to 01/02/2021
For 06/02/2021 sum all values from 06/02/2021 to 01/02/2021
For 31/01/2021 sum all values from 31/01/2021 to 01/01/2021
The output should look like, will be created as two separate tables:
Output
Any help would be appreciated.
Thanks
Sample data and structure: dbfiddle
For first part of query:
select date,
value,
sum(value) over (
order by to_date(date, 'DD/MM/YYYY')
rows between 4 preceding and current row) as five_day_period
from your_table_name
order by to_date(date, 'DD/MM/YYYY') desc;
For second part of query:
select date,
value,
sum(value)
over (
partition by regexp_replace(date, '[0-9]{2}/(.+)', '\1')
order by to_date(date, 'DD/MM/YYYY')
rows between unbounded preceding and current row) as month_to_date
from your_table_name
order by to_date(date, 'DD/MM/YYYY') desc;
Is there a way to create a date column combining one column having the year as string and one column containing a date-of-year (doy) as integer?
I am aware of methods like SELECT EXTRACT(DOW FROM TIMESTAMP '2001-02-16 20:38:40'); or SELECT to_char(date_trunc('year', now()) + interval '169 days', 'MM/DD') but when trying to replace the "hard coded" stings with the columns I always get some kind of an error.
SELECT s.id, s.year, s.doy,
((s.year||'-01-01')::date + (s.doy||' days')::interval )::date AS date
FROM table_name AS s
the (s.year||'-01-01') or (s.doy||' days') concats the column value with a required string and the ::date or ::interval changes the resulting string type
You can use the make_date() function and add the number of days directly because date + integer is a valid operation:
select make_date(s.year, 1, 1) + s.doy as date
from ...
timestamp with timezone is this - 2020-05-31T10:05:07Z
this is not working, despite referencing official documentation. I need to extract may 2020 or separate month and year to compare against May 2020
SELECT date_trunc('hour', TIMESTAMP '2020-05-31T10:05:07Z')
SELECT date_part('day', TIMESTAMP '2020-05-31T10:05:07Z');
If you want to check if a timestamp value is "may 2020", you have different options.
to_char(the_value, 'yyyy-mm') = '2020-05'
or
extract(month from the_value) = 5
and extract(year from the_value) = 2020
or
(extract(month from the_value), extract(year from the_value)) = (5, 2020)
extract() and date_part() are the same thing - but I prefer the standard compliant extract() version.
demo:db<>fiddle
You need to_char() to format a date or timestamp. Mon gives you the first three letters of a month name:
SELECT
to_char(
TIMESTAMP '2020-05-31T10:05:07Z',
'Mon YYYY'
)
Returning the entire month name you can use Month instead of Mon. But, for some reasons, the length of the Month value is fixed to the longest month name available. That means May is returned with right padded spaces. To avoid this, you need to add the modifier FM:
SELECT
to_char(
TIMESTAMP '2020-05-31T10:05:07Z',
'FMMonth YYYY'
)
I have a query that returns a field as month and year for example "Nov 2015" I want to get the number for the month, here I have to get number as "11".
You can use the to_date function that can parse input in a certain format into a 'real' date. Then with this date you can extract the month from it.
select EXTRACT(MONTH FROM to_date('Nov 2015', 'Mon YYYY'))
See http://www.postgresql.org/docs/current/static/functions-formatting.html for the formatting syntax and http://www.postgresql.org/docs/current/static/functions-datetime.html for the other datetime functions etc..
to_char()
select to_char(to_date('Nov 2015', 'Mon YYYY'), 'mm') month_no
and the query can be
select to_char(to_date(your_date_col, 'Mon YYYY'), 'mm') month_no
from table_name
If your date is timestamp , for example:"2017-01-24 23:00:00-03" (this is timestamp with time zone)
select to_char(your_date, 'MM') from your_table
Then the result would be in this case: "01"
You can use the function to_timestamp(text, text) and extract(field from timestamp):
SELECT EXTRACT(MONTH FROM TO_TIMESTAMP("Nov 2015", "Mon YYYY"));
see the documentation for to_timestamp and extract
I got a table:
CREATE TABLE TRANSACTION (
transaction_date date,
id_transaction int,
PRIMARY KEY (id_transaction)
);
and I want to compare the month of 'transaction_date' field with a number of month.
SELECT *
FROM TRANSACTION T
WHERE month = transaction_date;
but I don't know how to make this conversion.
You can use EXTRACT(MONTH FROM transaction_date)
SELECT *
FROM transaction
WHERE EXTRACT(MONTH FROM transaction_date) = 1;
sqlfiddle demo
As per the documentation:
EXTRACT (field FROM source)
The extract function retrieves subfields such as year or hour from
date/time values. source must be a value expression of type timestamp,
time, or interval.
SELECT *
FROM TRANSACTION T
WHERE EXTRACT(MONTH FROM TIMESTAMP transaction_date) = month;
month should be an integer between 1 (January) and 12 (December).