The strftime and strptime functions can be used to convert between DATE / TIMESTAMP values and strings. This is often required when parsing CSV files, displaying output to the user or transferring information between programs. Because there are many possible date representations, these functions accept a format string that describes how the date or timestamp should be structured.
strftime Examples
The strftime(timestamp, format) converts timestamps or dates to strings according to the specified pattern.
SELECT strftime(DATE '1992-03-02', '%d/%m/%Y');
02/03/1992
SELECT strftime(TIMESTAMP '1992-03-02 20:32:45', '%A, %-d %B %Y - %I:%M:%S %p');
Monday, 2 March 1992 - 08:32:45 PM
strptime Examples
The strptime(text, format) function converts strings to timestamps according to the specified pattern.
SELECT strptime('02/03/1992', '%d/%m/%Y');
1992-03-02 00:00:00
SELECT strptime('Monday, 2 March 1992 - 08:32:45 PM', '%A, %-d %B %Y - %I:%M:%S %p');
1992-03-02 20:32:45
The strptime function throws an error on failure:
SELECT strptime('02/50/1992', '%d/%m/%Y') AS x;
Invalid Input Error: Could not parse string "02/50/1992" according to format specifier "%d/%m/%Y"
02/50/1992
^
Error: Month out of range, expected a value between 1 and 12
To return NULL on failure, use the try_strptime function:
NULL
CSV Parsing
The date formats can also be specified during CSV parsing, either in the COPY statement or in the read_csv function. This can be done by either specifying a DATEFORMAT or a TIMESTAMPFORMAT (or both). DATEFORMAT will be used for converting dates, and TIMESTAMPFORMAT will be used for converting timestamps. Below are some examples for how to use this.
In a COPY statement:
COPY dates FROM 'test.csv' (DATEFORMAT '%d/%m/%Y', TIMESTAMPFORMAT '%A, %-d %B %Y - %I:%M:%S %p');
In a read_csv function:
SELECT *
FROM read_csv('test.csv', dateformat = '%m/%d/%Y');
Format Specifiers
Below is a full list of all available format specifiers.
| Specifier | Description | Example |
|---|---|---|
%a |
Abbreviated weekday name. | Sun, Mon, … |
%A |
Full weekday name. | Sunday, Monday, … |
%b |
Abbreviated month name. | Jan, Feb, …, Dec |
%B |
Full month name. | January, February, … |
%c |
ISO date and time representation | 1992-03-02 10:30:20 |
%d |
Day of the month as a zero-padded decimal. | 01, 02, …, 31 |
%-d |
Day of the month as a decimal number. | 1, 2, …, 30 |
%f |
Microsecond as a decimal number, zero-padded on the left. | 000000 - 999999 |
%g |
Millisecond as a decimal number, zero-padded on the left. | 000 - 999 |
%G |
ISO 8601 year with century representing the year that contains the greater part of the ISO week (see %V). |
0001, 0002, …, 2013, 2014, …, 9998, 9999 |
%H |
Hour (24-hour clock) as a zero-padded decimal number. | 00, 01, …, 23 |
%-H |
Hour (24-hour clock) as a decimal number. | 0, 1, …, 23 |
%I |
Hour (12-hour clock) as a zero-padded decimal number. | 01, 02, …, 12 |
%-I |
Hour (12-hour clock) as a decimal number. | 1, 2, … 12 |
%j |
Day of the year as a zero-padded decimal number. | 001, 002, …, 366 |
%-j |
Day of the year as a decimal number. | 1, 2, …, 366 |
%m |
Month as a zero-padded decimal number. | 01, 02, …, 12 |
%-m |
Month as a decimal number. | 1, 2, …, 12 |
%M |
Minute as a zero-padded decimal number. | 00, 01, …, 59 |
%-M |
Minute as a decimal number. | 0, 1, …, 59 |
%n |
Nanosecond as a decimal number, zero-padded on the left. | 000000000 - 999999999 |
%p |
Locale's AM or PM. | AM, PM |
%S |
Second as a zero-padded decimal number. | 00, 01, …, 59 |
%-S |
Second as a decimal number. | 0, 1, …, 59 |
%u |
ISO 8601 weekday as a decimal number where 1 is Monday. | 1, 2, …, 7 |
%U |
Week number of the year. Week 01 starts on the first Sunday of the year, so there can be week 00. Note that this is not compliant with the week date standard in ISO-8601. | 00, 01, …, 53 |
%V |
ISO 8601 week as a decimal number with Monday as the first day of the week. Week 01 is the week containing Jan 4. | 01, …, 53 |
%w |
Weekday as a decimal number. | 0, 1, …, 6 |
%W |
Week number of the year. Week 01 starts on the first Monday of the year, so there can be week 00. Note that this is not compliant with the week date standard in ISO-8601. | 00, 01, …, 53 |
%x |
ISO date representation | 1992-03-02 |
%X |
ISO time representation | 10:30:20 |
%y |
Year without century as a zero-padded decimal number. | 00, 01, …, 99 |
%-y |
Year without century as a decimal number. | 0, 1, …, 99 |
%Y |
Year with century as a decimal number. | 2013, 2019 etc. |
%z |
Time offset from UTC in the form ±HH:MM, ±HHMM, or ±HH. | -0700 |
%Z |
Time zone name. | Europe/Amsterdam |
%% |
A literal % character. |
% |