Datetime functions

GoogleSQL for BigQuery supports the following datetime functions.

All outputs are automatically formatted as per ISO 8601, separating date and time with aT.

Function list

Name	Summary
CURRENT_DATETIME	Returns the current date and time as a DATETIME value.
DATETIME	Constructs a DATETIME value.
DATETIME_ADD	Adds a specified time interval to a DATETIME value.
DATETIME_DIFF	Gets the number of unit boundaries between two DATETIME values at a particular time granularity.
DATETIME_SUB	Subtracts a specified time interval from a DATETIME value.
DATETIME_TRUNC	Truncates a DATETIME or TIMESTAMP value at a particular granularity.
EXTRACT	Extracts part of a date and time from a DATETIME value.
FORMAT_DATETIME	Formats a DATETIME value according to a specified format string.
LAST_DAY	Gets the last day in a specified time period that contains a DATETIME value.
PARSE_DATETIME	Converts a STRING value to a DATETIME value.

CURRENT_DATETIME

CURRENT_DATETIME([time_zone])

CURRENT_DATETIME

Description

Returns the current time as a DATETIME object. Parentheses are optional when called with no arguments.

This function supports an optional time_zone parameter. See Time zone definitions for information on how to specify a time zone.

The current date and time is recorded at the start of the query statement which contains this function, not when this specific function is evaluated.

Return Data Type

DATETIME

Example

SELECT CURRENT_DATETIME() as now;

/*----------------------------*
 | now                        |
 +----------------------------+
 | 2016-05-19T10:38:47.046465 |
 *----------------------------*/

DATETIME

1. DATETIME(year, month, day, hour, minute, second)
2. DATETIME(date_expression[, time_expression])
3. DATETIME(timestamp_expression [, time_zone])

Description

1. Constructs a DATETIME object using INT64 values representing the year, month, day, hour, minute, and second.
2. Constructs a DATETIME object using a DATE object and an optional TIME object.
3. Constructs a DATETIME object using a TIMESTAMP object. It supports an optional parameter to specify a time zone. If no time zone is specified, the default time zone, UTC, is used.

Return Data Type

DATETIME

Example

SELECT
  DATETIME(2008, 12, 25, 05, 30, 00) as datetime_ymdhms,
  DATETIME(TIMESTAMP "2008-12-25 05:30:00+00", "America/Los_Angeles") as datetime_tstz;

/*---------------------+---------------------*
 | datetime_ymdhms     | datetime_tstz       |
 +---------------------+---------------------+
 | 2008-12-25T05:30:00 | 2008-12-24T21:30:00 |
 *---------------------+---------------------*/

DATETIME_ADD

DATETIME_ADD(datetime_expression, INTERVAL int64_expression part)

Description

Adds int64_expression units of part to the DATETIME object.

DATETIME_ADD supports the following values for part:

• MICROSECOND
• MILLISECOND
• SECOND
• MINUTE
• HOUR
• DAY
• WEEK. Equivalent to 7 DAYs.
• MONTH
• QUARTER
• YEAR

Special handling is required for MONTH, QUARTER, and YEAR parts when the date is at (or near) the last day of the month. If the resulting month has fewer days than the original DATETIME's day, then the result day is the last day of the new month.

Return Data Type

DATETIME

Example

SELECT
  DATETIME "2008-12-25 15:30:00" as original_date,
  DATETIME_ADD(DATETIME "2008-12-25 15:30:00", INTERVAL 10 MINUTE) as later;

/*-----------------------------+------------------------*
 | original_date               | later                  |
 +-----------------------------+------------------------+
 | 2008-12-25T15:30:00         | 2008-12-25T15:40:00    |
 *-----------------------------+------------------------*/

DATETIME_DIFF

DATETIME_DIFF(end_datetime, start_datetime, granularity)

Description

Gets the number of unit boundaries between two DATETIME values (end_datetime - start_datetime) at a particular time granularity.

Definitions

• start_datetime: The starting DATETIME value.
• end_datetime: The ending DATETIME value.

• granularity: The datetime part that represents the granularity. If you have passed in DATETIME values for the first arguments, granularity can be:

  • MICROSECOND
  • MILLISECOND
  • SECOND
  • MINUTE
  • HOUR
  • DAY
  • WEEK: This date part begins on Sunday.
  • WEEK(<WEEKDAY>): This date part begins on WEEKDAY. Valid values for WEEKDAY are SUNDAY, MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, and SATURDAY.
  • ISOWEEK: Uses ISO 8601 week boundaries. ISO weeks begin on Monday.
  • MONTH
  • QUARTER
  • YEAR
  • ISOYEAR: Uses the ISO 8601 week-numbering year boundary. The ISO year boundary is the Monday of the first week whose Thursday belongs to the corresponding Gregorian calendar year.

Details

If end_datetime is earlier than start_datetime, the output is negative. Produces an error if the computation overflows, such as if the difference in microseconds between the two DATETIME values overflows.

Note: The behavior of the this function follows the type of arguments passed in. For example, DATETIME_DIFF(TIMESTAMP, TIMESTAMP, PART) behaves like TIMESTAMP_DIFF(TIMESTAMP, TIMESTAMP, PART).

Return Data Type

INT64

Example

SELECT
  DATETIME "2010-07-07 10:20:00" as first_datetime,
  DATETIME "2008-12-25 15:30:00" as second_datetime,
  DATETIME_DIFF(DATETIME "2010-07-07 10:20:00",
    DATETIME "2008-12-25 15:30:00", DAY) as difference;

/*----------------------------+------------------------+------------------------*
 | first_datetime             | second_datetime        | difference             |
 +----------------------------+------------------------+------------------------+
 | 2010-07-07T10:20:00        | 2008-12-25T15:30:00    | 559                    |
 *----------------------------+------------------------+------------------------*/

SELECT
  DATETIME_DIFF(DATETIME '2017-10-15 00:00:00',
    DATETIME '2017-10-14 00:00:00', DAY) as days_diff,
  DATETIME_DIFF(DATETIME '2017-10-15 00:00:00',
    DATETIME '2017-10-14 00:00:00', WEEK) as weeks_diff;

/*-----------+------------*
 | days_diff | weeks_diff |
 +-----------+------------+
 | 1         | 1          |
 *-----------+------------*/

The example above shows the result of DATETIME_DIFF for two DATETIMEs that are 24 hours apart. DATETIME_DIFF with the part WEEK returns 1 because DATETIME_DIFF counts the number of part boundaries in this range of DATETIMEs. Each WEEK begins on Sunday, so there is one part boundary between Saturday, 2017-10-14 00:00:00 and Sunday, 2017-10-15 00:00:00.

The following example shows the result of DATETIME_DIFF for two dates in different years. DATETIME_DIFF with the date part YEAR returns 3 because it counts the number of Gregorian calendar year boundaries between the two DATETIMEs. DATETIME_DIFF with the date part ISOYEAR returns 2 because the second DATETIME belongs to the ISO year 2015. The first Thursday of the 2015 calendar year was 2015-01-01, so the ISO year 2015 begins on the preceding Monday, 2014-12-29.

SELECT
  DATETIME_DIFF('2017-12-30 00:00:00',
    '2014-12-30 00:00:00', YEAR) AS year_diff,
  DATETIME_DIFF('2017-12-30 00:00:00',
    '2014-12-30 00:00:00', ISOYEAR) AS isoyear_diff;

/*-----------+--------------*
 | year_diff | isoyear_diff |
 +-----------+--------------+
 | 3         | 2            |
 *-----------+--------------*/

The following example shows the result of DATETIME_DIFF for two days in succession. The first date falls on a Monday and the second date falls on a Sunday. DATETIME_DIFF with the date part WEEK returns 0 because this time part uses weeks that begin on Sunday. DATETIME_DIFF with the date part WEEK(MONDAY) returns 1. DATETIME_DIFF with the date part ISOWEEK also returns 1 because ISO weeks begin on Monday.

SELECT
  DATETIME_DIFF('2017-12-18', '2017-12-17', WEEK) AS week_diff,
  DATETIME_DIFF('2017-12-18', '2017-12-17', WEEK(MONDAY)) AS week_weekday_diff,
  DATETIME_DIFF('2017-12-18', '2017-12-17', ISOWEEK) AS isoweek_diff;

/*-----------+-------------------+--------------*
 | week_diff | week_weekday_diff | isoweek_diff |
 +-----------+-------------------+--------------+
 | 0         | 1                 | 1            |
 *-----------+-------------------+--------------*/

DATETIME_SUB

DATETIME_SUB(datetime_expression, INTERVAL int64_expression part)

Description

Subtracts int64_expression units of part from the DATETIME.

DATETIME_SUB supports the following values for part:

• MICROSECOND
• MILLISECOND
• SECOND
• MINUTE
• HOUR
• DAY
• WEEK. Equivalent to 7 DAYs.
• MONTH
• QUARTER
• YEAR

Special handling is required for MONTH, QUARTER, and YEAR parts when the date is at (or near) the last day of the month. If the resulting month has fewer days than the original DATETIME's day, then the result day is the last day of the new month.

Return Data Type

DATETIME

Example

SELECT
  DATETIME "2008-12-25 15:30:00" as original_date,
  DATETIME_SUB(DATETIME "2008-12-25 15:30:00", INTERVAL 10 MINUTE) as earlier;

/*-----------------------------+------------------------*
 | original_date               | earlier                |
 +-----------------------------+------------------------+
 | 2008-12-25T15:30:00         | 2008-12-25T15:20:00    |
 *-----------------------------+------------------------*/

DATETIME_TRUNC

DATETIME_TRUNC(datetime_value, datetime_granularity)

DATETIME_TRUNC(timestamp_value, timestamp_granularity[, time_zone])

Description

Truncates a DATETIME or TIMESTAMP value at a particular granularity.

Definitions

• datetime_value: A DATETIME value to truncate.
• datetime_granularity: The truncation granularity for a DATETIME value. Date granularities and time granularities can be used.
• timestamp_value: A TIMESTAMP value to truncate.
• timestamp_granularity: The truncation granularity for a TIMESTAMP value. Date granularities and time granularities can be used.

• time_zone: A time zone to use with the TIMESTAMP value. Time zone parts can be used. Use this argument if you want to use a time zone other than the default time zone, UTC, as part of the truncate operation.

  Note: When truncating a timestamp to MINUTE or HOUR parts, this function determines the civil time of the timestamp in the specified (or default) time zone and subtracts the minutes and seconds (when truncating to HOUR) or the seconds (when truncating to MINUTE) from that timestamp. While this provides intuitive results in most cases, the result is non-intuitive near daylight savings transitions that are not hour-aligned.

Date granularity definitions

• DAY: The day in the Gregorian calendar year that contains the value to truncate.

• WEEK: The first day in the week that contains the value to truncate. Weeks begin on Sundays. WEEK is equivalent to WEEK(SUNDAY).

• WEEK(WEEKDAY): The first day in the week that contains the value to truncate. Weeks begin on WEEKDAY. WEEKDAY must be one of the following: SUNDAY, MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, or SATURDAY.

• ISOWEEK: The first day in the ISO 8601 week that contains the value to truncate. The ISO week begins on Monday. The first ISO week of each ISO year contains the first Thursday of the corresponding Gregorian calendar year.

• MONTH: The first day in the month that contains the value to truncate.

• QUARTER: The first day in the quarter that contains the value to truncate.

• YEAR: The first day in the year that contains the value to truncate.

• ISOYEAR: The first day in the ISO 8601 week-numbering year that contains the value to truncate. The ISO year is the Monday of the first week where Thursday belongs to the corresponding Gregorian calendar year.

Time granularity definitions

• MICROSECOND: If used, nothing is truncated from the value.

• MILLISECOND: The nearest lesser than or equal millisecond.

• SECOND: The nearest lesser than or equal second.

• MINUTE: The nearest lesser than or equal minute.

• HOUR: The nearest lesser than or equal hour.

Time zone part definitions

• MINUTE
• HOUR
• DAY
• WEEK
• WEEK(<WEEKDAY>)
• ISOWEEK
• MONTH
• QUARTER
• YEAR
• ISOYEAR

Details

The resulting value is always rounded to the beginning of granularity.

Return Data Type

The same data type as the first argument passed into this function.

Examples

SELECT
  DATETIME "2008-12-25 15:30:00" as original,
  DATETIME_TRUNC(DATETIME "2008-12-25 15:30:00", DAY) as truncated;

/*----------------------------+------------------------*
 | original                   | truncated              |
 +----------------------------+------------------------+
 | 2008-12-25T15:30:00        | 2008-12-25T00:00:00    |
 *----------------------------+------------------------*/

In the following example, the original DATETIME falls on a Sunday. Because the part is WEEK(MONDAY), DATE_TRUNC returns the DATETIME for the preceding Monday.

SELECT
 datetime AS original,
 DATETIME_TRUNC(datetime, WEEK(MONDAY)) AS truncated
FROM (SELECT DATETIME(TIMESTAMP "2017-11-05 00:00:00+00", "UTC") AS datetime);

/*---------------------+---------------------*
 | original            | truncated           |
 +---------------------+---------------------+
 | 2017-11-05T00:00:00 | 2017-10-30T00:00:00 |
 *---------------------+---------------------*/

In the following example, the original datetime_expression is in the Gregorian calendar year 2015. However, DATETIME_TRUNC with the ISOYEAR date part truncates the datetime_expression to the beginning of the ISO year, not the Gregorian calendar year. The first Thursday of the 2015 calendar year was 2015-01-01, so the ISO year 2015 begins on the preceding Monday, 2014-12-29. Therefore the ISO year boundary preceding the datetime_expression 2015-06-15 00:00:00 is 2014-12-29.

SELECT
  DATETIME_TRUNC('2015-06-15 00:00:00', ISOYEAR) AS isoyear_boundary,
  EXTRACT(ISOYEAR FROM DATETIME '2015-06-15 00:00:00') AS isoyear_number;

/*---------------------+----------------*
 | isoyear_boundary    | isoyear_number |
 +---------------------+----------------+
 | 2014-12-29T00:00:00 | 2015           |
 *---------------------+----------------*/

EXTRACT

EXTRACT(part FROM datetime_expression)

Description

Returns a value that corresponds to the specified part from a supplied datetime_expression.

Allowed part values are:

• MICROSECOND
• MILLISECOND
• SECOND
• MINUTE
• HOUR
• DAYOFWEEK: Returns values in the range [1,7] with Sunday as the first day of of the week.
• DAY
• DAYOFYEAR
• WEEK: Returns the week number of the date in the range [0, 53]. Weeks begin with Sunday, and dates prior to the first Sunday of the year are in week 0.
• WEEK(<WEEKDAY>): Returns the week number of datetime_expression in the range [0, 53]. Weeks begin on WEEKDAY. datetimes prior to the first WEEKDAY of the year are in week 0. Valid values for WEEKDAY are SUNDAY, MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, and SATURDAY.
• ISOWEEK: Returns the ISO 8601 week number of the datetime_expression. ISOWEEKs begin on Monday. Return values are in the range [1, 53]. The first ISOWEEK of each ISO year begins on the Monday before the first Thursday of the Gregorian calendar year.
• MONTH
• QUARTER
• YEAR
• ISOYEAR: Returns the ISO 8601 week-numbering year, which is the Gregorian calendar year containing the Thursday of the week to which date_expression belongs.
• DATE
• TIME

Returned values truncate lower order time periods. For example, when extracting seconds, EXTRACT truncates the millisecond and microsecond values.

Return Data Type

INT64, except in the following cases:

• If part is DATE, returns a DATE object.
• If part is TIME, returns a TIME object.

Examples

In the following example, EXTRACT returns a value corresponding to the HOUR time part.

SELECT EXTRACT(HOUR FROM DATETIME(2008, 12, 25, 15, 30, 00)) as hour;

/*------------------*
 | hour             |
 +------------------+
 | 15               |
 *------------------*/

In the following example, EXTRACT returns values corresponding to different time parts from a column of datetimes.

WITH Datetimes AS (
  SELECT DATETIME '2005-01-03 12:34:56' AS datetime UNION ALL
  SELECT DATETIME '2007-12-31' UNION ALL
  SELECT DATETIME '2009-01-01' UNION ALL
  SELECT DATETIME '2009-12-31' UNION ALL
  SELECT DATETIME '2017-01-02' UNION ALL
  SELECT DATETIME '2017-05-26'
)
SELECT
  datetime,
  EXTRACT(ISOYEAR FROM datetime) AS isoyear,
  EXTRACT(ISOWEEK FROM datetime) AS isoweek,
  EXTRACT(YEAR FROM datetime) AS year,
  EXTRACT(WEEK FROM datetime) AS week
FROM Datetimes
ORDER BY datetime;

/*---------------------+---------+---------+------+------*
 | datetime            | isoyear | isoweek | year | week |
 +---------------------+---------+---------+------+------+
 | 2005-01-03T12:34:56 | 2005    | 1       | 2005 | 1    |
 | 2007-12-31T00:00:00 | 2008    | 1       | 2007 | 52   |
 | 2009-01-01T00:00:00 | 2009    | 1       | 2009 | 0    |
 | 2009-12-31T00:00:00 | 2009    | 53      | 2009 | 52   |
 | 2017-01-02T00:00:00 | 2017    | 1       | 2017 | 1    |
 | 2017-05-26T00:00:00 | 2017    | 21      | 2017 | 21   |
 *---------------------+---------+---------+------+------*/

In the following example, datetime_expression falls on a Sunday. EXTRACT calculates the first column using weeks that begin on Sunday, and it calculates the second column using weeks that begin on Monday.

WITH table AS (SELECT DATETIME(TIMESTAMP "2017-11-05 00:00:00+00", "UTC") AS datetime)
SELECT
  datetime,
  EXTRACT(WEEK(SUNDAY) FROM datetime) AS week_sunday,
  EXTRACT(WEEK(MONDAY) FROM datetime) AS week_monday
FROM table;

/*---------------------+-------------+---------------*
 | datetime            | week_sunday | week_monday   |
 +---------------------+-------------+---------------+
 | 2017-11-05T00:00:00 | 45          | 44            |
 *---------------------+-------------+---------------*/

FORMAT_DATETIME

FORMAT_DATETIME(format_string, datetime_expr)

Description

Formats a DATETIME value according to a specified format string.

Definitions

• format_string: A STRING value that contains the format elements to use with datetime_expr.
• datetime_expr: A DATETIME value that represents the date and time to format.

Return Data Type

STRING

Examples

SELECT
  FORMAT_DATETIME("%c", DATETIME "2008-12-25 15:30:00")
  AS formatted;

/*--------------------------*
 | formatted                |
 +--------------------------+
 | Thu Dec 25 15:30:00 2008 |
 *--------------------------*/

SELECT
  FORMAT_DATETIME("%b-%d-%Y", DATETIME "2008-12-25 15:30:00")
  AS formatted;

/*-------------*
 | formatted   |
 +-------------+
 | Dec-25-2008 |
 *-------------*/

SELECT
  FORMAT_DATETIME("%b %Y", DATETIME "2008-12-25 15:30:00")
  AS formatted;

/*-------------*
 | formatted   |
 +-------------+
 | Dec 2008    |
 *-------------*/

LAST_DAY

LAST_DAY(datetime_expression[, date_part])

Description

Returns the last day from a datetime expression that contains the date. This is commonly used to return the last day of the month.

You can optionally specify the date part for which the last day is returned. If this parameter is not used, the default value is MONTH. LAST_DAY supports the following values for date_part:

• YEAR
• QUARTER
• MONTH
• WEEK. Equivalent to 7 DAYs.
• WEEK(<WEEKDAY>). <WEEKDAY> represents the starting day of the week. Valid values are SUNDAY, MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, and SATURDAY.
• ISOWEEK. Uses ISO 8601 week boundaries. ISO weeks begin on Monday.
• ISOYEAR. Uses the ISO 8601 week-numbering year boundary. The ISO year boundary is the Monday of the first week whose Thursday belongs to the corresponding Gregorian calendar year.

Return Data Type

DATE

Example

These both return the last day of the month:

SELECT LAST_DAY(DATETIME '2008-11-25', MONTH) AS last_day

/*------------*
 | last_day   |
 +------------+
 | 2008-11-30 |
 *------------*/

SELECT LAST_DAY(DATETIME '2008-11-25') AS last_day

/*------------*
 | last_day   |
 +------------+
 | 2008-11-30 |
 *------------*/

This returns the last day of the year:

SELECT LAST_DAY(DATETIME '2008-11-25 15:30:00', YEAR) AS last_day

/*------------*
 | last_day   |
 +------------+
 | 2008-12-31 |
 *------------*/

This returns the last day of the week for a week that starts on a Sunday:

SELECT LAST_DAY(DATETIME '2008-11-10 15:30:00', WEEK(SUNDAY)) AS last_day

/*------------*
 | last_day   |
 +------------+
 | 2008-11-15 |
 *------------*/

This returns the last day of the week for a week that starts on a Monday:

SELECT LAST_DAY(DATETIME '2008-11-10 15:30:00', WEEK(MONDAY)) AS last_day

/*------------*
 | last_day   |
 +------------+
 | 2008-11-16 |
 *------------*/

PARSE_DATETIME

PARSE_DATETIME(format_string, datetime_string)

Description

Converts a STRING value to a DATETIME value.

Definitions

• format_string: A STRING value that contains the format elements to use with datetime_string.
• datetime_string: A STRING value that represents the date and time to parse.

Details

Each element in datetime_string must have a corresponding element in format_string. The location of each element in format_string must match the location of each element in datetime_string.

-- This works because elements on both sides match.
SELECT PARSE_DATETIME("%a %b %e %I:%M:%S %Y", "Thu Dec 25 07:30:00 2008");

-- This produces an error because the year element is in different locations.
SELECT PARSE_DATETIME("%a %b %e %Y %I:%M:%S", "Thu Dec 25 07:30:00 2008");

-- This produces an error because one of the year elements is missing.
SELECT PARSE_DATETIME("%a %b %e %I:%M:%S", "Thu Dec 25 07:30:00 2008");

-- This works because %c can find all matching elements in datetime_string.
SELECT PARSE_DATETIME("%c", "Thu Dec 25 07:30:00 2008");

The format string fully supports most format elements, except for %P.

PARSE_DATETIME parses string according to the following rules:

• Unspecified fields. Any unspecified field is initialized from 1970-01-01 00:00:00.0. For example, if the year is unspecified then it defaults to 1970.
• Case insensitivity. Names, such as Monday and February, are case insensitive.
• Whitespace. One or more consecutive white spaces in the format string matches zero or more consecutive white spaces in the DATETIME string. Leading and trailing white spaces in the DATETIME string are always allowed, even if they are not in the format string.
• Format precedence. When two or more format elements have overlapping information, the last one generally overrides any earlier ones, with some exceptions. For example, both %F and %Y affect the year, so the earlier element overrides the later. See the descriptions of %s, %C, and %y in Supported Format Elements For DATETIME.
• Format divergence. %p can be used with am, AM, pm, and PM.

Return Data Type

DATETIME

Examples

The following examples parse a STRING literal as a DATETIME.

SELECT PARSE_DATETIME('%Y-%m-%d %H:%M:%S', '1998-10-18 13:45:55') AS datetime;

/*---------------------*
 | datetime            |
 +---------------------+
 | 1998-10-18T13:45:55 |
 *---------------------*/

SELECT PARSE_DATETIME('%m/%d/%Y %I:%M:%S %p', '8/30/2018 2:23:38 pm') AS datetime;

/*---------------------*
 | datetime            |
 +---------------------+
 | 2018-08-30T14:23:38 |
 *---------------------*/

The following example parses a STRING literal containing a date in a natural language format as a DATETIME.

SELECT PARSE_DATETIME('%A, %B %e, %Y','Wednesday, December 19, 2018')
  AS datetime;

/*---------------------*
 | datetime            |
 +---------------------+
 | 2018-12-19T00:00:00 |
 *---------------------*/