如何从 postgresql 中的时间戳获取小时、月份

Question

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');

Answer 1

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.

Answer 2

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'
    )