Date and time functions and operators

These functions and operators operate on {ref}date and time data types <date-time-data-types>.

Date and time operators

(at-time-zone-operator)=

Time zone conversion

The AT TIME ZONE operator sets the time zone of a timestamp:

SELECT timestamp '2012-10-31 01:00 UTC';
-- 2012-10-31 01:00:00.000 UTC

SELECT timestamp '2012-10-31 01:00 UTC' AT TIME ZONE 'America/Los_Angeles';
-- 2012-10-30 18:00:00.000 America/Los_Angeles

The AT LOCAL operator renders a datetime in the current session time zone:

SELECT timestamp '2012-10-31 01:00 UTC' AT LOCAL;
-- 2012-10-30 18:00:00.000 America/Los_Angeles  (session zone)

OVERLAPS

The OVERLAPS predicate tests whether two periods of time share any instant. Each operand is a row value of two elements:

• The first element is the period's start point, a datetime value.
• The second element is either the period's end point (a datetime value) or the period's length (an interval value, in which case the end is computed as start + interval).

SELECT (DATE '2020-01-01', DATE '2020-06-01') OVERLAPS (DATE '2020-05-01', DATE '2020-12-31');
-- true

SELECT (DATE '2020-01-01', DATE '2020-03-01') OVERLAPS (DATE '2020-05-01', DATE '2020-07-01');
-- false

SELECT (DATE '2020-01-01', INTERVAL '5' MONTH) OVERLAPS (DATE '2020-05-01', INTERVAL '7' MONTH);
-- true

If the start and end of an operand are given in reverse, they are normalized before evaluation. The half-open semantics mean that periods which touch only at a boundary (one period's end equal to the other's start) do not overlap; however, two periods that share the same start point always overlap.

If one endpoint of a period is NULL, the period is treated as open-ended on that side: its known endpoint still anchors the comparison, so the result is true whenever that known endpoint falls inside the other period, and NULL (unknown) only when the open side leaves the outcome undetermined.

Date and time functions

:::{data} current_date Returns the current date as of the start of the query. :::

:::{data} current_time Returns the current time with time zone as of the start of the query. :::

:::{data} current_timestamp Returns the current timestamp with time zone as of the start of the query, with 3 digits of subsecond precision, :::

:::{data} current_timestamp(p) :noindex: true

Returns the current {ref}timestamp with time zone <timestamp-with-time-zone-data-type> as of the start of the query, with p digits of subsecond precision:

SELECT current_timestamp(6);
-- 2020-06-24 08:25:31.759993 America/Los_Angeles

:::

:::{function} current_timezone() -> varchar Returns the current time zone in the format defined by IANA (e.g., America/Los_Angeles) or as fixed offset from UTC (e.g., +08:35) :::

:::{function} date(x) -> date This is an alias for CAST(x AS date). :::

:::{function} last_day_of_month(x) -> date Returns the last day of the month.

The type of x can be date, timestamp or timestamp with time zone. :::

:::{function} from_iso8601_timestamp(string) -> timestamp(3) with time zone Parses the ISO 8601 formatted date string, optionally with time and time zone, into a timestamp(3) with time zone. The time defaults to 00:00:00.000, and the time zone defaults to the session time zone:

SELECT from_iso8601_timestamp('2020-05-11');
-- 2020-05-11 00:00:00.000 America/Vancouver

SELECT from_iso8601_timestamp('2020-05-11T11:15:05');
-- 2020-05-11 11:15:05.000 America/Vancouver

SELECT from_iso8601_timestamp('2020-05-11T11:15:05.055+01:00');
-- 2020-05-11 11:15:05.055 +01:00

:::

:::{function} from_iso8601_timestamp_nanos(string) -> timestamp(9) with time zone Parses the ISO 8601 formatted date and time string. The time zone defaults to the session time zone:

SELECT from_iso8601_timestamp_nanos('2020-05-11T11:15:05');
-- 2020-05-11 11:15:05.000000000 America/Vancouver

SELECT from_iso8601_timestamp_nanos('2020-05-11T11:15:05.123456789+01:00');
-- 2020-05-11 11:15:05.123456789 +01:00

:::

:::{function} from_iso8601_date(string) -> date Parses the ISO 8601 formatted date string into a date. The date can be a calendar date, a week date using ISO week numbering, or year and day of year combined:

SELECT from_iso8601_date('2020-05-11');
-- 2020-05-11

SELECT from_iso8601_date('2020-W10');
-- 2020-03-02

SELECT from_iso8601_date('2020-123');
-- 2020-05-02

:::

:::{function} at_timezone(x, zone) -> timestamp(p) with time zone Converts x to a time zone specified in zone.

The type of x can be time with time zone or timestamp with time zone.

In the following example, the input timezone is GMT, which is seven hours ahead of America/Los_Angeles in November 2022:

SELECT at_timezone(TIMESTAMP '2022-11-01 09:08:07.321 GMT', 'America/Los_Angeles')
-- 2022-11-01 02:08:07.321 America/Los_Angeles

:::

:::{function} with_timezone(timestamp(p), zone) -> timestamp(p) with time zone Returns the timestamp specified in timestamp with the time zone specified in zone with precision p:

SELECT current_timezone()
-- America/New_York

SELECT with_timezone(TIMESTAMP '2022-11-01 09:08:07.321', 'America/Los_Angeles')
-- 2022-11-01 09:08:07.321 America/Los_Angeles

:::

:::{function} from_unixtime(unixtime) -> timestamp(3) with time zone Returns the UNIX timestamp unixtime as a timestamp with time zone. unixtime is the number of seconds since 1970-01-01 00:00:00 UTC. :::

:::{function} from_unixtime(unixtime, zone) -> timestamp(3) with time zone :noindex: true

Returns the UNIX timestamp unixtime as a timestamp with time zone using zone for the time zone. unixtime is the number of seconds since 1970-01-01 00:00:00 UTC. :::

:::{function} from_unixtime(unixtime, hours, minutes) -> timestamp(3) with time zone :noindex: true

Returns the UNIX timestamp unixtime as a timestamp with time zone using hours and minutes for the time zone offset. unixtime is the number of seconds since 1970-01-01 00:00:00 in double data type. :::

:::{function} from_unixtime_nanos(unixtime) -> timestamp(9) with time zone Returns the UNIX timestamp unixtime as a timestamp with time zone. unixtime is the number of nanoseconds since 1970-01-01 00:00:00.000000000 UTC:

SELECT from_unixtime_nanos(100);
-- 1970-01-01 00:00:00.000000100 UTC

SELECT from_unixtime_nanos(DECIMAL '1234');
-- 1970-01-01 00:00:00.000001234 UTC

SELECT from_unixtime_nanos(DECIMAL '1234.499');
-- 1970-01-01 00:00:00.000001234 UTC

SELECT from_unixtime_nanos(DECIMAL '-1234');
-- 1969-12-31 23:59:59.999998766 UTC

:::

:::{data} localtime Returns the current time as of the start of the query. :::

:::{data} localtimestamp Returns the current timestamp as of the start of the query, with 3 digits of subsecond precision. :::

:::{data} localtimestamp(p) :noindex: true

Returns the current {ref}timestamp <timestamp-data-type> as of the start of the query, with p digits of subsecond precision:

SELECT localtimestamp(6);
-- 2020-06-10 15:55:23.383628

:::

:::{function} now() -> timestamp(3) with time zone This is an alias for current_timestamp. :::

:::{function} to_iso8601(x) -> varchar Formats x as an ISO 8601 string.

The type of x can be date, time, time with timezone, timestamp or timestamp with time zone. :::

:::{function} to_milliseconds(interval) -> bigint Returns the day-to-second interval as milliseconds. :::

:::{function} to_unixtime(timestamp) -> double Returns timestamp as a UNIX timestamp. :::

:::{note} The following SQL-standard functions do not use parenthesis:

• current_date
• current_time
• current_timestamp
• localtime
• localtimestamp :::

Truncation function

The date_trunc function supports the following units:

The above examples use the timestamp 2001-08-22 03:04:05.321 as the input.

:::{function} date_trunc(unit, x) -> [same as input] Returns x truncated to unit:

SELECT date_trunc('day' , TIMESTAMP '2022-10-20 05:10:00');
-- 2022-10-20 00:00:00.000

SELECT date_trunc('month' , TIMESTAMP '2022-10-20 05:10:00');
-- 2022-10-01 00:00:00.000

SELECT date_trunc('year', TIMESTAMP '2022-10-20 05:10:00');
-- 2022-01-01 00:00:00.000

:::

(datetime-interval-functions)=

Interval functions

The functions in this section support the following interval units:

:::{function} date_add(unit, value, timestamp) -> [same as input] Adds an interval value of type unit to timestamp. Subtraction can be performed by using a negative value:

SELECT date_add('second', 86, TIMESTAMP '2020-03-01 00:00:00');
-- 2020-03-01 00:01:26.000

SELECT date_add('hour', 9, TIMESTAMP '2020-03-01 00:00:00');
-- 2020-03-01 09:00:00.000

SELECT date_add('day', -1, TIMESTAMP '2020-03-01 00:00:00 UTC');
-- 2020-02-29 00:00:00.000 UTC

:::

:::{function} date_diff(unit, timestamp1, timestamp2) -> bigint Returns timestamp2 - timestamp1 expressed in terms of unit:

SELECT date_diff('second', TIMESTAMP '2020-03-01 00:00:00', TIMESTAMP '2020-03-02 00:00:00');
-- 86400

SELECT date_diff('hour', TIMESTAMP '2020-03-01 00:00:00 UTC', TIMESTAMP '2020-03-02 00:00:00 UTC');
-- 24

SELECT date_diff('day', DATE '2020-03-01', DATE '2020-03-02');
-- 1

SELECT date_diff('second', TIMESTAMP '2020-06-01 12:30:45.000000000', TIMESTAMP '2020-06-02 12:30:45.123456789');
-- 86400

SELECT date_diff('millisecond', TIMESTAMP '2020-06-01 12:30:45.000000000', TIMESTAMP '2020-06-02 12:30:45.123456789');
-- 86400123

:::

Duration function

The parse_duration function supports the following units:

:::{function} parse_duration(string) -> interval Parses string of format value unit into an interval, where value is fractional number of unit values:

SELECT parse_duration('42.8ms');
-- 0 00:00:00.043

SELECT parse_duration('3.81 d');
-- 3 19:26:24.000

SELECT parse_duration('5m');
-- 0 00:05:00.000

:::

:::{function} human_readable_seconds(double) -> varchar Formats the double value of seconds into a human-readable string containing weeks, days, hours, minutes, and seconds:

SELECT human_readable_seconds(96);
-- 1 minute, 36 seconds

SELECT human_readable_seconds(3762);
-- 1 hour, 2 minutes, 42 seconds

SELECT human_readable_seconds(56363463);
-- 93 weeks, 1 day, 8 hours, 31 minutes, 3 seconds

:::

MySQL date functions

The functions in this section use a format string that is compatible with the MySQL date_parse and str_to_date functions. The following table, based on the MySQL manual, describes the format specifiers:

:::{warning} The following specifiers are not currently supported: %D %U %u %V %w %X :::

:::{function} date_format(timestamp, format) -> varchar Formats timestamp as a string using format:

SELECT date_format(TIMESTAMP '2022-10-20 05:10:00', '%m-%d-%Y %H');
-- 10-20-2022 05

:::

:::{js:function} date_parse(string, format) → timestamp(3) Parses string into a timestamp using format:

SELECT date_parse('2022/10/20/05', '%Y/%m/%d/%H');
-- 2022-10-20 05:00:00.000

:::

Java date functions

The functions in this section use a format string that is compatible with JodaTime's DateTimeFormat pattern format.

:::{function} format_datetime(timestamp, format) -> varchar Formats timestamp as a string using format. :::

:::{function} parse_datetime(string, format) -> timestamp with time zone Parses string into a timestamp with time zone using format. :::

Extraction function

The extract function supports the following fields:

The types supported by the extract function vary depending on the field to be extracted. Most fields support all date and time types.

::::{function} extract(field FROM x) -> bigint Returns field from x:

SELECT extract(YEAR FROM TIMESTAMP '2022-10-20 05:10:00');
-- 2022

:::{note} This SQL-standard function uses special syntax for specifying the arguments. ::: ::::

Convenience extraction functions

:::{function} day(x) -> bigint Returns the day of the month from x.

The type of x can be date, timestamp or timestamp with time zone. :::

:::{function} day_of_month(x) -> bigint This is an alias for {func}day. :::

:::{function} day_of_week(x) -> bigint Returns the ISO day of the week from x. The value ranges from 1 (Monday) to 7 (Sunday).

The type of x can be date, timestamp or timestamp with time zone. :::

:::{function} day_of_year(x) -> bigint Returns the day of the year from x. The value ranges from 1 to 366.

The type of x can be date, timestamp or timestamp with time zone. :::

:::{function} dow(x) -> bigint This is an alias for {func}day_of_week. :::

:::{function} doy(x) -> bigint This is an alias for {func}day_of_year. :::

:::{function} hour(x) -> bigint Returns the hour of the day from x. The value ranges from 0 to 23.

The type of x can be time, time with time zone, timestamp or timestamp with time zone. :::

:::{function} millisecond(x) -> bigint Returns the millisecond of the second from x.

The type of x can be time, time with time zone, timestamp or timestamp with time zone. :::

:::{function} minute(x) -> bigint Returns the minute of the hour from x.

The type of x can be time, time with time zone, timestamp or timestamp with time zone. :::

:::{function} month(x) -> bigint Returns the month of the year from x.

The type of x can be date, timestamp or timestamp with time zone. :::

:::{function} quarter(x) -> bigint Returns the quarter of the year from x. The value ranges from 1 to 4.

The type of x can be date, timestamp or timestamp with time zone. :::

:::{function} second(x) -> bigint Returns the second of the minute from x.

The type of x can be time, time with time zone, timestamp or timestamp with time zone. :::

:::{function} timezone_hour(timestamp) -> bigint Returns the hour of the time zone offset from timestamp. :::

:::{function} timezone_minute(timestamp) -> bigint Returns the minute of the time zone offset from timestamp. :::

:::{function} week(x) -> bigint Returns the ISO week of the year from x. The value ranges from 1 to 53.

The type of x can be date, timestamp or timestamp with time zone. :::

:::{function} week_of_year(x) -> bigint This is an alias for {func}week. :::

:::{function} year(x) -> bigint Returns the year from x.

The type of x can be date, timestamp or timestamp with time zone. :::

:::{function} year_of_week(x) -> bigint Returns the year of the ISO week from x.

The type of x can be date, timestamp or timestamp with time zone. :::

:::{function} yow(x) -> bigint This is an alias for {func}year_of_week. :::

:::{function} timezone(timestamp(p) with time zone) -> varchar

Returns the timezone identifier from timestamp(p) with time zone. The format of the returned identifier is identical to the format used in the input timestamp:

SELECT timezone(TIMESTAMP '2024-01-01 12:00:00 Asia/Tokyo'); -- Asia/Tokyo
SELECT timezone(TIMESTAMP '2024-01-01 12:00:00 +01:00'); -- +01:00
SELECT timezone(TIMESTAMP '2024-02-29 12:00:00 UTC'); -- UTC

:::

:::{function} timezone(time(p) with time zone) -> varchar :no-index: Returns the timezone identifier from a time(p) with time zone. The format of the returned identifier is identical to the format used in the input time:

SELECT timezone(TIME '12:00:00+09:00'); -- +09:00

:::