Date/Time and Interval Functions and Operatorsedit

Elasticsearch SQL offers a wide range of facilities for performing date/time manipulations.

Intervalsedit

A common requirement when dealing with date/time in general revolves around the notion of interval, a topic that is worth exploring in the context of Elasticsearch and Elasticsearch SQL.

Elasticsearch has comprehensive support for date math both inside index names and queries. Inside Elasticsearch SQL the former is supported as is by passing the expression in the table name, while the latter is supported through the standard SQL INTERVAL.

The table below shows the mapping between Elasticsearch and Elasticsearch SQL:

Elasticsearch

Elasticsearch SQL

Index/Table datetime math

<index-{now/M{YYYY.MM}}>

Query date/time math

1y

INTERVAL 1 YEAR

2M

INTERVAL 2 MONTH

3w

INTERVAL 21 DAY

4d

INTERVAL 4 DAY

5h

INTERVAL 5 HOUR

6m

INTERVAL 6 MINUTE

7s

INTERVAL 7 SECOND

INTERVAL allows either YEAR and MONTH to be mixed together or DAY, HOUR, MINUTE and SECOND.

Elasticsearch SQL accepts also the plural for each time unit (e.g. both YEAR and YEARS are valid).

Example of the possible combinations below:

Interval

Description

INTERVAL '1-2' YEAR TO MONTH

1 year and 2 months

INTERVAL '3 4' DAYS TO HOURS

3 days and 4 hours

INTERVAL '5 6:12' DAYS TO MINUTES

5 days, 6 hours and 12 minutes

INTERVAL '3 4:56:01' DAY TO SECOND

3 days, 4 hours, 56 minutes and 1 second

INTERVAL '2 3:45:01.23456789' DAY TO SECOND

2 days, 3 hours, 45 minutes, 1 second and 234567890 nanoseconds

INTERVAL '123:45' HOUR TO MINUTES

123 hours and 45 minutes

INTERVAL '65:43:21.0123' HOUR TO SECONDS

65 hours, 43 minutes, 21 seconds and 12300000 nanoseconds

INTERVAL '45:01.23' MINUTES TO SECONDS

45 minutes, 1 second and 230000000 nanoseconds

Comparisonedit

Date/time fields can be compared to date math expressions with the equality (=) and IN operators:

SELECT hire_date FROM emp WHERE hire_date = '1987-03-01||+4y/y';

       hire_date
------------------------
1991-01-26T00:00:00.000Z
1991-10-22T00:00:00.000Z
1991-09-01T00:00:00.000Z
1991-06-26T00:00:00.000Z
1991-08-30T00:00:00.000Z
1991-12-01T00:00:00.000Z
SELECT hire_date FROM emp WHERE hire_date IN ('1987-03-01||+2y/M', '1987-03-01||+3y/M');

       hire_date
------------------------
1989-03-31T00:00:00.000Z
1990-03-02T00:00:00.000Z

Operatorsedit

Basic arithmetic operators (+, -, *) support date/time parameters as indicated below:

SELECT INTERVAL 1 DAY + INTERVAL 53 MINUTES AS result;

    result
---------------
+1 00:53:00
SELECT CAST('1969-05-13T12:34:56' AS DATETIME) + INTERVAL 49 YEARS AS result;

       result
--------------------
2018-05-13T12:34:56Z
SELECT - INTERVAL '49-1' YEAR TO MONTH result;

    result
---------------
-49-1
SELECT INTERVAL '1' DAY - INTERVAL '2' HOURS AS result;

    result
---------------
+0 22:00:00
SELECT CAST('2018-05-13T12:34:56' AS DATETIME) - INTERVAL '2-8' YEAR TO MONTH AS result;

       result
--------------------
2015-09-13T12:34:56Z
SELECT -2 * INTERVAL '3' YEARS AS result;

    result
---------------
-6-0

Functionsedit

Functions that target date/time.

CURRENT_DATE/CURDATEedit

Synopsis:

CURRENT_DATE
CURRENT_DATE()
CURDATE()

Input: none

Output: date

Description: Returns the date (no time part) when the current query reached the server. It can be used both as a keyword: CURRENT_DATE or as a function with no arguments: CURRENT_DATE().

Unlike CURRENT_DATE, CURDATE() can only be used as a function with no arguments and not as a keyword.

This method always returns the same value for its every occurrence within the same query.

SELECT CURRENT_DATE AS result;

         result
------------------------
2018-12-12
SELECT CURRENT_DATE() AS result;

         result
------------------------
2018-12-12
SELECT CURDATE() AS result;

         result
------------------------
2018-12-12

Typically, this function (as well as its twin TODAY()) function is used for relative date filtering:

SELECT first_name FROM emp WHERE hire_date > TODAY() - INTERVAL 35 YEARS ORDER BY first_name ASC LIMIT 5;

 first_name
------------
Alejandro
Amabile
Anneke
Anoosh
Basil

CURRENT_TIME/CURTIMEedit

Synopsis:

CURRENT_TIME
CURRENT_TIME([precision]) 
CURTIME

Input:

fractional digits; optional

Output: time

Description: Returns the time when the current query reached the server. As a function, CURRENT_TIME() accepts precision as an optional parameter for rounding the second fractional digits (nanoseconds). The default precision is 3, meaning a milliseconds precision current time will be returned.

This method always returns the same value for its every occurrence within the same query.

SELECT CURRENT_TIME AS result;

         result
------------------------
12:31:27.237Z
SELECT CURRENT_TIME() AS result;

         result
------------------------
12:31:27.237Z
SELECT CURTIME() AS result;

         result
------------------------
12:31:27.237Z
SELECT CURRENT_TIME(1) AS result;

         result
------------------------
12:31:27.2Z

Typically, this function is used for relative date/time filtering:

SELECT first_name FROM emp WHERE CAST(hire_date AS TIME) > CURRENT_TIME() - INTERVAL 20 MINUTES ORDER BY first_name ASC LIMIT 5;

  first_name
---------------
Alejandro
Amabile
Anneke
Anoosh
Arumugam

Currently, using a precision greater than 6 doesn’t make any difference to the output of the function as the maximum number of second fractional digits returned is 6.

CURRENT_TIMESTAMPedit

Synopsis:

CURRENT_TIMESTAMP
CURRENT_TIMESTAMP([precision]) 

Input:

fractional digits; optional

Output: date/time

Description: Returns the date/time when the current query reached the server. As a function, CURRENT_TIMESTAMP() accepts precision as an optional parameter for rounding the second fractional digits (nanoseconds). The default precision is 3, meaning a milliseconds precision current date/time will be returned.

This method always returns the same value for its every occurrence within the same query.

SELECT CURRENT_TIMESTAMP AS result;

         result
------------------------
2018-12-12T14:48:52.448Z
SELECT CURRENT_TIMESTAMP() AS result;

         result
------------------------
2018-12-12T14:48:52.448Z
SELECT CURRENT_TIMESTAMP(1) AS result;

         result
------------------------
2018-12-12T14:48:52.4Z

Typically, this function (as well as its twin NOW()) function is used for relative date/time filtering:

SELECT first_name FROM emp WHERE hire_date > NOW() - INTERVAL 100 YEARS ORDER BY first_name ASC LIMIT 5;

  first_name
---------------
Alejandro
Amabile
Anneke
Anoosh
Arumugam

Currently, using a precision greater than 6 doesn’t make any difference to the output of the function as the maximum number of second fractional digits returned is 6.

DATE_ADD/DATEADD/TIMESTAMP_ADD/TIMESTAMPADDedit

Synopsis:

DATE_ADD(
    string_exp, 
    integer_exp, 
    datetime_exp) 

Input:

string expression denoting the date/time unit to add to the date/datetime. If null, the function returns null.

integer expression denoting how many times the above unit should be added to/from the date/datetime, if a negative value is used it results to a subtraction from the date/datetime. If null, the function returns null.

date/datetime expression. If null, the function returns null.

Output: datetime

Description: Add the given number of date/time units to a date/datetime. If the number of units is negative then it’s subtracted from the date/datetime.

If the second argument is a long there is possibility of truncation since an integer value will be extracted and used from that long.

Datetime units to add/subtract

unit

abbreviations

year

years, yy, yyyy

quarter

quarters, qq, q

month

months, mm, m

dayofyear

dy, y

day

days, dd, d

week

weeks, wk, ww

weekday

weekdays, dw

hour

hours, hh

minute

minutes, mi, n

second

seconds, ss, s

millisecond

milliseconds, ms

microsecond

microseconds, mcs

nanosecond

nanoseconds, ns

SELECT DATE_ADD('years', 10, '2019-09-04T11:22:33.000Z'::datetime) AS "+10 years";

      +10 years
------------------------
2029-09-04T11:22:33.000Z
SELECT DATE_ADD('week', 10, '2019-09-04T11:22:33.000Z'::datetime) AS "+10 weeks";

      +10 weeks
------------------------
2019-11-13T11:22:33.000Z
SELECT DATE_ADD('seconds', -1234, '2019-09-04T11:22:33.000Z'::datetime) AS "-1234 seconds";

      -1234 seconds
------------------------
2019-09-04T11:01:59.000Z
SELECT DATE_ADD('qq', -417, '2019-09-04'::date) AS "-417 quarters";

      -417 quarters
------------------------
1915-06-04T00:00:00.000Z
SELECT DATE_ADD('minutes', 9235, '2019-09-04'::date) AS "+9235 minutes";

      +9235 minutes
------------------------
2019-09-10T09:55:00.000Z

DATE_DIFF/DATEDIFF/TIMESTAMP_DIFF/TIMESTAMPDIFFedit

Synopsis:

DATE_DIFF(
    string_exp, 
    datetime_exp, 
    datetime_exp) 

Input:

string expression denoting the date/time unit difference between the following two date/datetime expressions. If null, the function returns null.

start date/datetime expression. If null, the function returns null.

end date/datetime expression. If null, the function returns null.

Output: integer

Description: Subtract the second argument from the third argument and return their difference in multiples of the unit specified in the first argument. If the second argument (start) is greater than the third argument (end), then negative values are returned.

Datetime difference units

unit

abbreviations

year

years, yy, yyyy

quarter

quarters, qq, q

month

months, mm, m

dayofyear

dy, y

day

days, dd, d

week

weeks, wk, ww

weekday

weekdays, dw

hour

hours, hh

minute

minutes, mi, n

second

seconds, ss, s

millisecond

milliseconds, ms

microsecond

microseconds, mcs

nanosecond

nanoseconds, ns

SELECT DATE_DIFF('years', '2019-09-04T11:22:33.000Z'::datetime, '2032-09-04T22:33:11.000Z'::datetime) AS "diffInYears";

      diffInYears
------------------------
13
SELECT DATE_DIFF('week', '2019-09-04T11:22:33.000Z'::datetime, '2016-12-08T22:33:11.000Z'::datetime) AS "diffInWeeks";

      diffInWeeks
------------------------
-143
SELECT DATE_DIFF('seconds', '2019-09-04T11:22:33.123Z'::datetime, '2019-07-12T22:33:11.321Z'::datetime) AS "diffInSeconds";

      diffInSeconds
------------------------
-4625362
SELECT DATE_DIFF('qq', '2019-09-04'::date, '2025-04-25'::date) AS "diffInQuarters";

      diffInQuarters
------------------------
23

For hour and minute, DATEDIFF doesn’t do any rounding, but instead first truncates the more detailed time fields on the 2 dates to zero and then calculates the subtraction.

SELECT DATEDIFF('hours', '2019-11-10T12:10:00.000Z'::datetime, '2019-11-10T23:59:59.999Z'::datetime) AS "diffInHours";

      diffInHours
------------------------
11
SELECT DATEDIFF('minute', '2019-11-10T12:10:00.000Z'::datetime, '2019-11-10T12:15:59.999Z'::datetime) AS "diffInMinutes";

      diffInMinutes
------------------------
5
SELECT DATE_DIFF('minutes', '2019-09-04'::date, '2015-08-17T22:33:11.567Z'::datetime) AS "diffInMinutes";

      diffInMinutes
------------------------
-2128407

DATE_FORMATedit

Synopsis:

DATE_FORMAT(
    date_exp/datetime_exp/time_exp, 
    string_exp) 

Input:

date/datetime/time expression. If null, the function returns null.

format pattern. If null or an empty string, the function returns null.

Output: string

Description: Returns the date/datetime/time as a string using the format specified in the 2nd argument. The formatting pattern is one of the specifiers used in the MySQL DATE_FORMAT() function.

If the 1st argument is of type time, then pattern specified by the 2nd argument cannot contain date related units (e.g. dd, MM, yyyy, etc.). If it contains such units an error is returned. Ranges for month and day specifiers (%c, %D, %d, %e, %m) start at one, unlike MySQL, where they start at zero, due to the fact that MySQL permits the storing of incomplete dates such as 2014-00-00. Elasticsearch in this case returns an error.

SELECT DATE_FORMAT(CAST('2020-04-05' AS DATE), '%d/%m/%Y') AS "date";

      date
------------------
05/04/2020
SELECT DATE_FORMAT(CAST('2020-04-05T11:22:33.987654' AS DATETIME), '%d/%m/%Y %H:%i:%s.%f') AS "datetime";

      datetime
------------------
05/04/2020 11:22:33.987654
SELECT DATE_FORMAT(CAST('23:22:33.987' AS TIME), '%H %i %s.%f') AS "time";

      time
------------------
23 22 33.987000

DATE_PARSEedit

Synopsis:

DATE_PARSE(
    string_exp, 
    string_exp) 

Input:

date expression as a string. If null or an empty string, the function returns null.

parsing pattern. If null or an empty string, the function returns null.

Output: date

Description: Returns a date by parsing the 1st argument using the format specified in the 2nd argument. The parsing format pattern used is the one from java.time.format.DateTimeFormatter.

If the parsing pattern does not contain all valid date units (e.g. HH:mm:ss, dd-MM HH:mm:ss, etc.) an error is returned as the function needs to return a value of date type which will contain date part.

SELECT DATE_PARSE('07/04/2020', 'dd/MM/yyyy') AS "date";

   date
-----------
2020-04-07

The resulting date will have the time zone specified by the user through the time_zone/timezone REST/driver parameters with no conversion applied.

{
    "query" : "SELECT DATE_PARSE('07/04/2020', 'dd/MM/yyyy') AS \"date\"",
    "time_zone" : "Europe/Athens"
}

   date
------------
2020-04-07T00:00:00.000+03:00

DATETIME_FORMATedit

Synopsis:

DATETIME_FORMAT(
    date_exp/datetime_exp/time_exp, 
    string_exp) 

Input:

date/datetime/time expression. If null, the function returns null.

format pattern. If null or an empty string, the function returns null.

Output: string

Description: Returns the date/datetime/time as a string using the format specified in the 2nd argument. The formatting pattern used is the one from java.time.format.DateTimeFormatter.

If the 1st argument is of type time, then pattern specified by the 2nd argument cannot contain date related units (e.g. dd, MM, yyyy, etc.). If it contains such units an error is returned.

SELECT DATETIME_FORMAT(CAST('2020-04-05' AS DATE), 'dd/MM/yyyy') AS "date";

      date
------------------
05/04/2020
SELECT DATETIME_FORMAT(CAST('2020-04-05T11:22:33.987654' AS DATETIME), 'dd/MM/yyyy HH:mm:ss.SS') AS "datetime";

      datetime
------------------
05/04/2020 11:22:33.98
SELECT DATETIME_FORMAT(CAST('11:22:33.987' AS TIME), 'HH mm ss.S') AS "time";

      time
------------------
11 22 33.9

DATETIME_PARSEedit

Synopsis:

DATETIME_PARSE(
    string_exp, 
    string_exp) 

Input:

datetime expression as a string. If null or an empty string, the function returns null.

parsing pattern. If null or an empty string, the function returns null.

Output: datetime

Description: Returns a datetime by parsing the 1st argument using the format specified in the 2nd argument. The parsing format pattern used is the one from java.time.format.DateTimeFormatter.

If the parsing pattern contains only date or only time units (e.g. dd/MM/yyyy, HH:mm:ss, etc.) an error is returned as the function needs to return a value of datetime type which must contain both.

SELECT DATETIME_PARSE('07/04/2020 10:20:30.123', 'dd/MM/yyyy HH:mm:ss.SSS') AS "datetime";

      datetime
------------------------
2020-04-07T10:20:30.123Z
SELECT DATETIME_PARSE('10:20:30 07/04/2020 Europe/Berlin', 'HH:mm:ss dd/MM/yyyy VV') AS "datetime";

      datetime
------------------------
2020-04-07T08:20:30.000Z

If timezone is not specified in the datetime string expression and the parsing pattern, the resulting datetime will have the time zone specified by the user through the time_zone/timezone REST/driver parameters with no conversion applied.

{
    "query" : "SELECT DATETIME_PARSE('10:20:30 07/04/2020', 'HH:mm:ss dd/MM/yyyy') AS \"datetime\"",
    "time_zone" : "Europe/Athens"
}

      datetime
-----------------------------
2020-04-07T10:20:30.000+03:00

TIME_PARSEedit

Synopsis:

TIME_PARSE(
    string_exp, 
    string_exp) 

Input:

time expression as a string. If null or an empty string, the function returns null.

parsing pattern. If null or an empty string, the function returns null.

Output: time

Description: Returns a time by parsing the 1st argument using the format specified in the 2nd argument. The parsing format pattern used is the one from java.time.format.DateTimeFormatter.

If the parsing pattern contains only date units (e.g. dd/MM/yyyy) an error is returned as the function needs to return a value of time type which will contain only time.

SELECT TIME_PARSE('10:20:30.123', 'HH:mm:ss.SSS') AS "time";

     time
---------------
10:20:30.123Z
SELECT TIME_PARSE('10:20:30-01:00', 'HH:mm:ssXXX') AS "time";

     time
---------------
11:20:30.000Z

If timezone is not specified in the time string expression and the parsing pattern, the resulting time will have the offset of the time zone specified by the user through the time_zone/timezone REST/driver parameters at the Unix epoch date (1970-01-01) with no conversion applied.

{
    "query" : "SELECT DATETIME_PARSE('10:20:30', 'HH:mm:ss') AS \"time\"",
    "time_zone" : "Europe/Athens"
}

      time
------------------------------------
10:20:30.000+02:00

DATE_PART/DATEPARTedit

Synopsis:

DATE_PART(
    string_exp, 
    datetime_exp) 

Input:

string expression denoting the unit to extract from the date/datetime. If null, the function returns null.

date/datetime expression. If null, the function returns null.

Output: integer

Description: Extract the specified unit from a date/datetime. It’s similar to EXTRACT but with different names and aliases for the units and provides more options (e.g.: TZOFFSET).

Datetime units to extract

unit

abbreviations

year

years, yy, yyyy

quarter

quarters, qq, q

month

months, mm, m

dayofyear

dy, y

day

days, dd, d

week

weeks, wk, ww

weekday

weekdays, dw

hour

hours, hh

minute

minutes, mi, n

second

seconds, ss, s

millisecond

milliseconds, ms

microsecond

microseconds, mcs

nanosecond

nanoseconds, ns

tzoffset

tz

SELECT DATE_PART('year', '2019-09-22T11:22:33.123Z'::datetime) AS "years";

   years
----------
2019
SELECT DATE_PART('mi', '2019-09-04T11:22:33.123Z'::datetime) AS mins;

   mins
-----------
22
SELECT DATE_PART('quarters', CAST('2019-09-24' AS DATE)) AS quarter;

   quarter
-------------
3
SELECT DATE_PART('month', CAST('2019-09-24' AS DATE)) AS month;

   month
-------------
9

For week and weekday the unit is extracted using the non-ISO calculation, which means that a given week is considered to start from Sunday, not Monday.

SELECT DATE_PART('week', '2019-09-22T11:22:33.123Z'::datetime) AS week;

   week
----------
39

The tzoffset returns the total number of minutes (signed) that represent the time zone’s offset.

SELECT DATE_PART('tzoffset', '2019-09-04T11:22:33.123+05:15'::datetime) AS tz_mins;

   tz_mins
--------------
315
SELECT DATE_PART('tzoffset', '2019-09-04T11:22:33.123-03:49'::datetime) AS tz_mins;

   tz_mins
--------------
-229

DATE_TRUNC/DATETRUNCedit

Synopsis:

DATE_TRUNC(
    string_exp, 
    datetime_exp/interval_exp) 

Input:

string expression denoting the unit to which the date/datetime/interval should be truncated to. If null, the function returns null.

date/datetime/interval expression. If null, the function returns null.

Output: datetime/interval

Description: Truncate the date/datetime/interval to the specified unit by setting all fields that are less significant than the specified one to zero (or one, for day, day of week and month). If the first argument is week and the second argument is of interval type, an error is thrown since the interval data type doesn’t support a week time unit.

Datetime truncation units

unit

abbreviations

millennium

millennia

century

centuries

decade

decades

year

years, yy, yyyy

quarter

quarters, qq, q

month

months, mm, m

week

weeks, wk, ww

day

days, dd, d

hour

hours, hh

minute

minutes, mi, n

second

seconds, ss, s

millisecond

milliseconds, ms

microsecond

microseconds, mcs

nanosecond

nanoseconds, ns

SELECT DATE_TRUNC('millennium', '2019-09-04T11:22:33.123Z'::datetime) AS millennium;

      millennium
------------------------
2000-01-01T00:00:00.000Z
SELECT DATETRUNC('week', '2019-08-24T11:22:33.123Z'::datetime) AS week;

      week
------------------------
2019-08-19T00:00:00.000Z
SELECT DATE_TRUNC('mi', '2019-09-04T11:22:33.123Z'::datetime) AS mins;

      mins
------------------------
2019-09-04T11:22:00.000Z
SELECT DATE_TRUNC('decade', CAST('2019-09-04' AS DATE)) AS decades;

      decades
------------------------
2010-01-01T00:00:00.000Z
SELECT DATETRUNC('quarters', CAST('2019-09-04' AS DATE)) AS quarter;

      quarter
------------------------
2019-07-01T00:00:00.000Z
SELECT DATE_TRUNC('centuries', INTERVAL '199-5' YEAR TO MONTH) AS centuries;

      centuries
------------------
 +100-0
SELECT DATE_TRUNC('hours', INTERVAL '17 22:13:12' DAY TO SECONDS) AS hour;

      hour
------------------
+17 22:00:00
SELECT DATE_TRUNC('days', INTERVAL '19 15:24:19' DAY TO SECONDS) AS day;

      day
------------------
+19 00:00:00

FORMATedit

Synopsis:

FORMAT(
    date_exp/datetime_exp/time_exp, 
    string_exp) 

Input:

date/datetime/time expression. If null, the function returns null.

format pattern. If null or an empty string, the function returns null.

Output: string

Description: Returns the date/datetime/time as a string using the format specified in the 2nd argument. The formatting pattern used is the one from Microsoft SQL Server Format Specification.

If the 1st argument is of type time, then pattern specified by the 2nd argument cannot contain date related units (e.g. dd, MM, yyyy, etc.). If it contains such units an error is returned.
Format specifier F will be working similar to format specifier f. It will return the fractional part of seconds, and the number of digits will be same as of the number of Fs provided as input (up to 9 digits). Result will contain 0 appended in the end to match with number of F provided. e.g.: for a time part 10:20:30.1234 and pattern HH:mm:ss.FFFFFF, the output string of the function would be: 10:20:30.123400.
Format specifier y will return year-of-era instead of one/two low-order digits. eg.: For year 2009, y will be returning 2009 instead of 9. For year 43, y format specifier will return 43. - Special characters like " , \ and % will be returned as it is without any change. eg.: formatting date 17-sep-2020 with %M will return %9

SELECT FORMAT(CAST('2020-04-05' AS DATE), 'dd/MM/yyyy') AS "date";

      date
------------------
05/04/2020
SELECT FORMAT(CAST('2020-04-05T11:22:33.987654' AS DATETIME), 'dd/MM/yyyy HH:mm:ss.ff') AS "datetime";

      datetime
------------------
05/04/2020 11:22:33.98
SELECT FORMAT(CAST('11:22:33.987' AS TIME), 'HH mm ss.f') AS "time";

      time
------------------
11 22 33.9

TO_CHARedit

Synopsis:

TO_CHAR(
    date_exp/datetime_exp/time_exp, 
    string_exp) 

Input:

date/datetime/time expression. If null, the function returns null.

format pattern. If null or an empty string, the function returns null.

Output: string

Description: Returns the date/datetime/time as a string using the format specified in the 2nd argument. The formatting pattern conforms to PostgreSQL Template Patterns for Date/Time Formatting.

If the 1st argument is of type time, then the pattern specified by the 2nd argument cannot contain date related units (e.g. dd, MM, YYYY, etc.). If it contains such units an error is returned.
The result of the patterns TZ and tz (time zone abbreviations) in some cases differ from the results returned by the TO_CHAR in PostgreSQL. The reason is that the time zone abbreviations specified by the JDK are different from the ones specified by PostgreSQL. This function might show an actual time zone abbreviation instead of the generic LMT or empty string or offset returned by the PostgreSQL implementation. The summer/daylight markers might also differ between the two implementations (e.g. will show HT instead of HST for Hawaii).
The FX, TM, SP pattern modifiers are not supported and will show up as FX, TM, SP literals in the output.

SELECT TO_CHAR(CAST('2020-04-05' AS DATE), 'DD/MM/YYYY') AS "date";

      date
------------------
05/04/2020
SELECT TO_CHAR(CAST('2020-04-05T11:22:33.987654' AS DATETIME), 'DD/MM/YYYY HH24:MI:SS.FF2') AS "datetime";

      datetime
------------------
05/04/2020 11:22:33.98
SELECT TO_CHAR(CAST('23:22:33.987' AS TIME), 'HH12 MI SS.FF1') AS "time";

      time
------------------
11 22 33.9

DAY_OF_MONTH/DOM/DAYedit

Synopsis:

DAY_OF_MONTH(datetime_exp) 

Input:

date/datetime expression. If null, the function returns null.

Output: integer

Description: Extract the day of the month from a date/datetime.

SELECT DAY_OF_MONTH(CAST('2018-02-19T10:23:27Z' AS TIMESTAMP)) AS day;

      day
---------------
19

DAY_OF_WEEK/DAYOFWEEK/DOWedit

Synopsis:

DAY_OF_WEEK(datetime_exp) 

Input:

date/datetime expression. If null, the function returns null.

Output: integer

Description: Extract the day of the week from a date/datetime. Sunday is 1, Monday is 2, etc.

SELECT DAY_OF_WEEK(CAST('2018-02-19T10:23:27Z' AS TIMESTAMP)) AS day;

      day
---------------
2

DAY_OF_YEAR/DOYedit

Synopsis:

DAY_OF_YEAR(datetime_exp) 

Input:

date/datetime expression. If null, the function returns null.

Output: integer

Description: Extract the day of the year from a date/datetime.

SELECT DAY_OF_YEAR(CAST('2018-02-19T10:23:27Z' AS TIMESTAMP)) AS day;

      day
---------------
50

DAY_NAME/DAYNAMEedit

Synopsis:

DAY_NAME(datetime_exp) 

Input:

date/datetime expression. If null, the function returns null.

Output: string

Description: Extract the day of the week from a date/datetime in text format (Monday, Tuesday…​).

SELECT DAY_NAME(CAST('2018-02-19T10:23:27Z' AS TIMESTAMP)) AS day;

      day
---------------
Monday

HOUR_OF_DAY/HOURedit

Synopsis:

HOUR_OF_DAY(datetime_exp) 

Input:

date/datetime expression. If null, the function returns null.

Output: integer

Description: Extract the hour of the day from a date/datetime.

SELECT HOUR_OF_DAY(CAST('2018-02-19T10:23:27Z' AS TIMESTAMP)) AS hour;

     hour
---------------
10

ISO_DAY_OF_WEEK/ISODAYOFWEEK/ISODOW/IDOWedit

Synopsis:

ISO_DAY_OF_WEEK(datetime_exp) 

Input:

date/datetime expression. If null, the function returns null.

Output: integer

Description: Extract the day of the week from a date/datetime, following the ISO 8601 standard. Monday is 1, Tuesday is 2, etc.

SELECT ISO_DAY_OF_WEEK(CAST('2018-02-19T10:23:27Z' AS TIMESTAMP)) AS day;

      day
---------------
1

ISO_WEEK_OF_YEAR/ISOWEEKOFYEAR/ISOWEEK/IWOY/IWedit

Synopsis:

ISO_WEEK_OF_YEAR(datetime_exp) 

Input:

date/datetime expression. If null, the function returns null.

Output: integer

Description: Extract the week of the year from a date/datetime, following ISO 8601 standard. The first week of a year is the first week with a majority (4 or more) of its days in January.

SELECT ISO_WEEK_OF_YEAR(CAST('2018-02-19T10:23:27Z' AS TIMESTAMP)) AS week;

     week
---------------
8

MINUTE_OF_DAYedit

Synopsis:

MINUTE_OF_DAY(datetime_exp) 

Input:

date/datetime expression. If null, the function returns null.

Output: integer

Description: Extract the minute of the day from a date/datetime.

SELECT MINUTE_OF_DAY(CAST('2018-02-19T10:23:27Z' AS TIMESTAMP)) AS minute;

    minute
---------------
623

MINUTE_OF_HOUR/MINUTEedit

Synopsis:

MINUTE_OF_HOUR(datetime_exp) 

Input:

date/datetime expression. If null, the function returns null.

Output: integer

Description: Extract the minute of the hour from a date/datetime.

SELECT MINUTE_OF_HOUR(CAST('2018-02-19T10:23:27Z' AS TIMESTAMP)) AS minute;

    minute
---------------
23

MONTH_OF_YEAR/MONTHedit

Synopsis:

MONTH(datetime_exp) 

Input:

date/datetime expression. If null, the function returns null.

Output: integer

Description: Extract the month of the year from a date/datetime.

SELECT MONTH_OF_YEAR(CAST('2018-02-19T10:23:27Z' AS TIMESTAMP)) AS month;

     month
---------------
2

MONTH_NAME/MONTHNAMEedit

Synopsis:

MONTH_NAME(datetime_exp) 

Input:

date/datetime expression. If null, the function returns null.

Output: string

Description: Extract the month from a date/datetime in text format (January, February…​).

SELECT MONTH_NAME(CAST('2018-02-19T10:23:27Z' AS TIMESTAMP)) AS month;

     month
---------------
February

NOWedit

Synopsis:

NOW()

Input: none

Output: datetime

Description: This function offers the same functionality as CURRENT_TIMESTAMP() function: returns the datetime when the current query reached the server. This method always returns the same value for its every occurrence within the same query.

SELECT NOW() AS result;

         result
------------------------
2018-12-12T14:48:52.448Z

Typically, this function (as well as its twin CURRENT_TIMESTAMP()) function is used for relative date/time filtering:

SELECT first_name FROM emp WHERE hire_date > NOW() - INTERVAL 100 YEARS ORDER BY first_name ASC LIMIT 5;

  first_name
---------------
Alejandro
Amabile
Anneke
Anoosh
Arumugam

SECOND_OF_MINUTE/SECONDedit

Synopsis:

SECOND_OF_MINUTE(datetime_exp) 

Input:

date/datetime expression. If null, the function returns null.

Output: integer

Description: Extract the second of the minute from a date/datetime.

SELECT SECOND_OF_MINUTE(CAST('2018-02-19T10:23:27Z' AS TIMESTAMP)) AS second;

    second
---------------
27

QUARTERedit

Synopsis:

QUARTER(datetime_exp) 

Input:

date/datetime expression. If null, the function returns null.

Output: integer

Description: Extract the year quarter the date/datetime falls in.

SELECT QUARTER(CAST('2018-02-19T10:23:27Z' AS TIMESTAMP)) AS quarter;

    quarter
---------------
1

TODAYedit

Synopsis:

TODAY()

Input: none

Output: date

Description: This function offers the same functionality as CURRENT_DATE() function: returns the date when the current query reached the server. This method always returns the same value for its every occurrence within the same query.

SELECT TODAY() AS result;

         result
------------------------
2018-12-12

Typically, this function (as well as its twin CURRENT_TIMESTAMP()) function is used for relative date filtering:

SELECT first_name FROM emp WHERE hire_date > TODAY() - INTERVAL 35 YEARS ORDER BY first_name ASC LIMIT 5;

 first_name
------------
Alejandro
Amabile
Anneke
Anoosh
Basil

WEEK_OF_YEAR/WEEKedit

Synopsis:

WEEK_OF_YEAR(datetime_exp) 

Input:

date/datetime expression. If null, the function returns null.

Output: integer

Description: Extract the week of the year from a date/datetime.

SELECT WEEK(CAST('1988-01-05T09:22:10Z' AS TIMESTAMP)) AS week, ISOWEEK(CAST('1988-01-05T09:22:10Z' AS TIMESTAMP)) AS isoweek;

      week     |   isoweek
---------------+---------------
2              |1

YEARedit

Synopsis:

YEAR(datetime_exp) 

Input:

date/datetime expression. If null, the function returns null.

Output: integer

Description: Extract the year from a date/datetime.

SELECT YEAR(CAST('2018-02-19T10:23:27Z' AS TIMESTAMP)) AS year;

     year
---------------
2018

EXTRACTedit

Synopsis:

EXTRACT(
    datetime_function  
    FROM datetime_exp) 

Input:

date/time function name

date/datetime expression

Output: integer

Description: Extract fields from a date/datetime by specifying the name of a datetime function. The following

SELECT EXTRACT(DAY_OF_YEAR FROM CAST('2018-02-19T10:23:27Z' AS TIMESTAMP)) AS day;

      day
---------------
50

is the equivalent to

SELECT DAY_OF_YEAR(CAST('2018-02-19T10:23:27Z' AS TIMESTAMP)) AS day;

      day
---------------
50