Timestamp functions in Dataflow SQL

Cloud Dataflow SQL supports the following TIMESTAMP functions.

CURRENT_TIMESTAMP

CURRENT_TIMESTAMP()

Description

Parentheses are optional. This function handles leap seconds by smearing them across a window of 20 hours around the inserted leap second. CURRENT_TIMESTAMP() produces a TIMESTAMP value that is continuous, non-ambiguous, has exactly 60 seconds per minute and does not repeat values over the leap second.

Supported Input Types

Not applicable

Result Data Type

TIMESTAMP

Example

SELECT CURRENT_TIMESTAMP() as now;

+----------------------------------+
| now                              |
+----------------------------------+
| 2016-05-16 18:12:47.145482639+00 |
+----------------------------------+

EXTRACT

EXTRACT(part FROM timestamp_expression [AT TIME ZONE tz_spec])

Description

Returns an INT64 value that corresponds to the specified part from a supplied timestamp_expression.

Allowed part values are:

  • NANOSECOND
  • MICROSECOND
  • MILLISECOND
  • SECOND
  • MINUTE
  • HOUR
  • DAYOFWEEK
  • DAY
  • DAYOFYEAR
  • 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.
  • DATETIME
  • TIME

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

See Timezone definitions for information on how to specify a time zone.

Return Data Type

Generally INT64. Returns an allowed part value.

Examples

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

SELECT EXTRACT(DAY
  FROM TIMESTAMP "2008-12-25 15:30:00" AT TIME ZONE "America/Los_Angeles")
  AS the_day;

+------------+
| the_day    |
+------------+
| 25         |
+------------+

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

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

+------------------------+---------+---------+------+
| timestamp              | isoyear | isoweek | year |
+------------------------+---------+---------+------+
| 2005-01-03 12:34:56+00 | 2005    | 1       | 2005 |
| 2007-12-31 00:00:00+00 | 2008    | 1       | 2007 |
| 2009-01-01 00:00:00+00 | 2009    | 1       | 2009 |
| 2009-12-31 00:00:00+00 | 2009    | 53      | 2009 |
| 2017-01-02 00:00:00+00 | 2017    | 1       | 2017 |
| 2017-05-26 00:00:00+00 | 2017    | 21      | 2017 |
+------------------------+---------+---------+------+

STRING

STRING(timestamp_expression[, timezone])

Description

Converts a timestamp_expression to a STRING data type. Supports an optional parameter to specify a time zone. See Timezone definitions for information on how to specify a time zone.

Return Data Type

STRING

Example

SELECT STRING(TIMESTAMP "2008-12-25 15:30:00", "America/Los_Angeles") as string;

+-------------------------------+
| string                        |
+-------------------------------+
| 2008-12-25 07:30:00-08        |
+-------------------------------+

TIMESTAMP

TIMESTAMP(
  string_expression[, timezone] |
)

Description

  • string_expression[, timezone]: Converts a STRING expression to a TIMESTAMP data type. string_expression must include a timestamp literal. If string_expression includes a timezone in the timestamp literal, do not include an explicit timezone argument.

This function supports an optional parameter to specify a time zone. If no time zone is specified, the default time zone, which is implementation defined, is used.

Return Data Type

TIMESTAMP

Examples

In these examples, a time zone is specified.

SELECT CAST(
  TIMESTAMP("2008-12-25 15:30:00", "America/Los_Angeles") AS STRING
) AS timestamp_str;

+------------------------+
| timestamp_str          |
+------------------------+
| 2008-12-25 23:30:00+00 |
+------------------------+

SELECT CAST(
  TIMESTAMP("2008-12-25 15:30:00 America/Los_Angeles") AS STRING
) AS timestamp_str_timezone;

+------------------------+
| timestamp_str_timezone |
+------------------------+
| 2008-12-25 23:30:00+00 |
+------------------------+

In these examples, assume that the default time zone is UTC.

SELECT CAST(
  TIMESTAMP("2008-12-25 15:30:00") AS STRING
) AS timestamp_str;

+------------------------+
| timestamp_str          |
+------------------------+
| 2008-12-25 15:30:00+00 |
+------------------------+

TIMESTAMP_ADD

TIMESTAMP_ADD(timestamp_expression, INTERVAL int64_expression date_part)

Description

Adds int64_expression units of date_part to the timestamp, independent of any time zone.

TIMESTAMP_ADD supports the following values for date_part:

  • NANOSECOND
  • MICROSECOND
  • MILLISECOND
  • SECOND
  • MINUTE
  • HOUR. Equivalent to 60 MINUTEs.
  • DAY. Equivalent to 24 HOURs.

Return Data Types

TIMESTAMP

Example

SELECT
  TIMESTAMP "2008-12-25 15:30:00 UTC" as original,
  TIMESTAMP_ADD(TIMESTAMP "2008-12-25 15:30:00 UTC", INTERVAL 10 MINUTE) AS later;

+------------------------+------------------------+
| original               | later                  |
+------------------------+------------------------+
| 2008-12-25 15:30:00+00 | 2008-12-25 15:40:00+00 |
+------------------------+------------------------+

TIMESTAMP_SUB

TIMESTAMP_SUB(timestamp_expression, INTERVAL int64_expression date_part)

Description

Subtracts int64_expression units of date_part from the timestamp, independent of any time zone.

TIMESTAMP_SUB supports the following values for date_part:

  • NANOSECOND
  • MICROSECOND
  • MILLISECOND
  • SECOND
  • MINUTE
  • HOUR. Equivalent to 60 MINUTEs.
  • DAY. Equivalent to 24 HOURs.

Return Data Type

TIMESTAMP

Example

SELECT
  TIMESTAMP "2008-12-25 15:30:00 UTC" as original,
  TIMESTAMP_SUB(TIMESTAMP "2008-12-25 15:30:00 UTC", INTERVAL 10 MINUTE) AS earlier;

+------------------------+------------------------+
| original               | earlier                |
+------------------------+------------------------+
| 2008-12-25 15:30:00+00 | 2008-12-25 15:20:00+00 |
+------------------------+------------------------+

TIMESTAMP_DIFF

TIMESTAMP_DIFF(timestamp_expression, timestamp_expression, date_part)

Description

Returns the number of whole specified date_part intervals between two timestamps. The first timestamp_expression represents the later date; if the first timestamp_expression is earlier than the second timestamp_expression, the output is negative. Throws an error if the computation overflows the result type, such as if the difference in nanoseconds between the two timestamps would overflow an INT64 value.

TIMESTAMP_DIFF supports the following values for date_part:

  • NANOSECOND
  • MICROSECOND
  • MILLISECOND
  • SECOND
  • MINUTE
  • HOUR. Equivalent to 60 MINUTEs.
  • DAY. Equivalent to 24 HOURs.

Return Data Type

INT64

Example

SELECT
  TIMESTAMP "2010-07-07 10:20:00 UTC" as later_timestamp,
  TIMESTAMP "2008-12-25 15:30:00 UTC" as earlier_timestamp,
  TIMESTAMP_DIFF(TIMESTAMP "2010-07-07 10:20:00 UTC",
    TIMESTAMP "2008-12-25 15:30:00 UTC", HOUR) AS hours;

+------------------------+------------------------+-------+
| later_timestamp        | earlier_timestamp      | hours |
+------------------------+------------------------+-------+
| 2010-07-07 10:20:00+00 | 2008-12-25 15:30:00+00 | 13410 |
+------------------------+------------------------+-------+

In the following example, the first timestamp occurs before the second timestamp, resulting in a negative output.

SELECT TIMESTAMP_DIFF(TIMESTAMP "2018-08-14", TIMESTAMP "2018-10-14", DAY);

+---------------+
| negative_diff |
+---------------+
| -61           |
+---------------+

TIMESTAMP_TRUNC

TIMESTAMP_TRUNC(timestamp_expression, date_part[, time_zone])

Description

Truncates a timestamp to the granularity of date_part.

TIMESTAMP_TRUNC supports the following values for date_part:

  • NANOSECOND
  • MICROSECOND
  • MILLISECOND
  • SECOND
  • MINUTE
  • HOUR
  • DAY
  • MONTH
  • QUARTER
  • YEAR
  • ISOYEAR: Truncates timestamp_expression to the preceding 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.

TIMESTAMP_TRUNC function supports an optional time_zone parameter. This parameter applies to the following date_parts:

  • MINUTE
  • HOUR
  • DAY
  • MONTH
  • QUARTER
  • YEAR

Use this parameter if you want to use a time zone other than the default time zone, which is implementation defined, as part of the truncate operation.

When truncating a TIMESTAMP to MINUTE orHOUR, TIMESTAMP_TRUNC 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.

Return Data Type

TIMESTAMP

Examples

SELECT
  TIMESTAMP_TRUNC(TIMESTAMP '2008-12-25 15:30:00', DAY, 'UTC') as utc,
  TIMESTAMP_TRUNC(TIMESTAMP '2008-12-25 15:30:00', DAY, 'America/Los_Angeles') as la;

+------------------------+------------------------+
| utc                    | la                     |
+------------------------+------------------------+
| 2008-12-25 00:00:00+00 | 2008-12-25 08:00:00+00 |
+------------------------+------------------------+

In the following example, timestamp_expression has a time zone offset of +12. The first column shows the timestamp_expression in UTC time. The second column shows the output of TIMESTAMP_TRUNC using weeks that start on Monday. Because the timestamp_expression falls on a Sunday in UTC, TIMESTAMP_TRUNC truncates it to the preceding Monday. The third column shows the same function with the optional Timezone definition argument 'Pacific/Auckland'. Here the function truncates the timestamp_expression using New Zealand Daylight Time, where it falls on a Monday.

In the following example, the original timestamp_expression is in the Gregorian calendar year 2015. However, TIMESTAMP_TRUNC with the ISOYEAR date part truncates the timestamp_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 timestamp_expression 2015-06-15 00:00:00+00 is 2014-12-29.

SELECT
  TIMESTAMP_TRUNC('2015-06-15 00:00:00+00', ISOYEAR) AS isoyear_boundary,
  EXTRACT(ISOYEAR FROM TIMESTAMP '2015-06-15 00:00:00+00') AS isoyear_number;

+------------------------+----------------+
| isoyear_boundary       | isoyear_number |
+------------------------+----------------+
| 2014-12-29 00:00:00+00 | 2015           |
+------------------------+----------------+

FORMAT_TIMESTAMP

FORMAT_TIMESTAMP(format_string, timestamp[, time_zone])

Description

Formats a timestamp according to the specified format_string.

See Supported Format Elements For TIMESTAMP for a list of format elements that this function supports.

Return Data Type

STRING

Example

SELECT FORMAT_TIMESTAMP("%c", TIMESTAMP "2008-12-25 15:30:00", "America/Los_Angeles")
  AS formatted;

+--------------------------+
| formatted                |
+--------------------------+
| Thu Dec 25 07:30:00 2008 |
+--------------------------+

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

+-------------+
| formatted   |
+-------------+
| Dec-25-2008 |
+-------------+

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

+-------------+
| formatted   |
+-------------+
| Dec 2008    |
+-------------+

PARSE_TIMESTAMP

PARSE_TIMESTAMP(format_string, string[, time_zone])

Description

Uses a format_string and a string representation of a timestamp to return a TIMESTAMP object.

When using PARSE_TIMESTAMP, keep the following in mind:

  • Unspecified fields. Any unspecified field is initialized from 1970-01-01 00:00:00.0. This initialization value uses the time zone specified by the function's time zone argument, if present. If not, the initialization value uses the default time zone, which is implementation defined. For instance, if the year is unspecified then it defaults to 1970, and so on.
  • Case insensitive names. Names, such as Monday, February, and so on, are case insensitive.
  • Whitespace. One or more consecutive white spaces in the format string matches zero or more consecutive white spaces in the timestamp string. In addition, leading and trailing white spaces in the timestamp string are always allowed -- even if they are not in the format string.
  • Format precedence. When two (or more) format elements have overlapping information (for example both %F and %Y affect the year), the last one generally overrides any earlier ones, with some exceptions (see the descriptions of %s, %C, and %y).

Return Data Type

TIMESTAMP

Example

SELECT PARSE_TIMESTAMP("%c", "Thu Dec 25 07:30:00 2008", "America/Los_Angeles") as parsed;

+------------------------+
| parsed                 |
+------------------------+
| 2008-12-25 15:30:00+00 |
+------------------------+

TIMESTAMP_SECONDS

TIMESTAMP_SECONDS(int64_expression)

Description

Interprets int64_expression as the number of seconds since 1970-01-01 00:00:00 UTC.

Return Data Type

TIMESTAMP

Example

SELECT TIMESTAMP_SECONDS(1230219000) as timestamp;

+------------------------+
| timestamp              |
+------------------------+
| 2008-12-25 15:30:00+00 |
+------------------------+

TIMESTAMP_MILLIS

TIMESTAMP_MILLIS(int64_expression)

Description

Interprets int64_expression as the number of milliseconds since 1970-01-01 00:00:00 UTC.

Return Data Type

TIMESTAMP

Example

SELECT TIMESTAMP_MILLIS(1230219000000) as timestamp;

+------------------------+
| timestamp              |
+------------------------+
| 2008-12-25 15:30:00+00 |
+------------------------+

UNIX_SECONDS

UNIX_SECONDS(timestamp_expression)

Description

Returns the number of seconds since 1970-01-01 00:00:00 UTC. Truncates higher levels of precision.

Return Data Type

INT64

Example

SELECT UNIX_SECONDS(TIMESTAMP "2008-12-25 15:30:00 UTC") as seconds;

+------------+
| seconds    |
+------------+
| 1230219000 |
+------------+

UNIX_MILLIS

UNIX_MILLIS(timestamp_expression)

Description

Returns the number of milliseconds since 1970-01-01 00:00:00 UTC. Truncates higher levels of precision.

Return Data Type

INT64

Example

SELECT UNIX_MILLIS(TIMESTAMP "2008-12-25 15:30:00 UTC") as millis;

+---------------+
| millis        |
+---------------+
| 1230219000000 |
+---------------+

TIMESTAMP_FROM_UNIX_SECONDS

TIMESTAMP_FROM_UNIX_SECONDS(int64_expression)

Description

Interprets int64_expression as the number of seconds since 1970-01-01 00:00:00 UTC and creates a timestamp.

Return Data Type

TIMESTAMP

Example

SELECT TIMESTAMP_FROM_UNIX_SECONDS(1230219000) as timestamp;

+------------------------+
| timestamp              |
+------------------------+
| 2008-12-25 15:30:00+00 |
+------------------------+

TIMESTAMP_FROM_UNIX_MILLIS

TIMESTAMP_FROM_UNIX_MILLIS(int64_expression)

Description

Interprets int64_expression as the number of milliseconds since 1970-01-01 00:00:00 UTC and creates a timestamp.

Return Data Type

TIMESTAMP

Example

SELECT TIMESTAMP_FROM_UNIX_MILLIS(1230219000000) as timestamp;

+------------------------+
| timestamp              |
+------------------------+
| 2008-12-25 15:30:00+00 |
+------------------------+

Supported format elements for TIMESTAMP

Unless otherwise noted, TIMESTAMP functions that use format strings support the following elements:

Format element Description
%A The full weekday name.
%a The abbreviated weekday name.
%B The full month name.
%b or %h The abbreviated month name.
%C The century (a year divided by 100 and truncated to an integer) as a decimal number (00-99).
%c The date and time representation in the format %a %b %e %T %Y.
%D The date in the format %m/%d/%y.
%d The day of the month as a decimal number (01-31).
%e The day of month as a decimal number (1-31); single digits are preceded by a space.
%F The date in the format %Y-%m-%d.
%G The ISO 8601 year with century as a decimal number. Each ISO year begins on the Monday before the first Thursday of the Gregorian calendar year. Note that %G and %Y may produce different results near Gregorian year boundaries, where the Gregorian year and ISO year can diverge.
%g The ISO 8601 year with century as a decimal number (00-99). Each ISO year begins on the Monday before the first Thursday of the Gregorian calendar year. Note that %g and %y may produce different results near Gregorian year boundaries, where the Gregorian year and ISO year can diverge.
%H The hour (24-hour clock) as a decimal number (00-23).
%I The hour (12-hour clock) as a decimal number (01-12).
%j The day of the year as a decimal number (001-366).
%k The hour (24-hour clock) as a decimal number (0-23); single digits are preceded by a space.
%l The hour (12-hour clock) as a decimal number (1-12); single digits are preceded by a space.
%M The minute as a decimal number (00-59).
%m The month as a decimal number (01-12).
%n A newline character.
%P Either am or pm.
%p Either AM or PM.
%Q The quarter as a decimal number (1-4).
%R The time in the format %H:%M.
%r The 12-hour clock time using AM/PM notation.
%S The second as a decimal number (00-60).
%s The number of seconds since 1970-01-01 00:00:00 UTC. Always overrides all other format elements, independent of where %s appears in the string. If multiple %s elements appear, then the last one takes precedence.
%T The time in the format %H:%M:%S.
%t A tab character.
%U The week number of the year (Sunday as the first day of the week) as a decimal number (00-53).
%u The weekday (Monday as the first day of the week) as a decimal number (1-7).
%V The ISO 8601 week number of the year (Monday as the first day of the week) as a decimal number (01-53). If the week containing January 1 has four or more days in the new year, then it is week 1; otherwise it is week 53 of the previous year, and the next week is week 1.
%W The week number of the year (Monday as the first day of the week) as a decimal number (00-53).
%w The weekday (Sunday as the first day of the week) as a decimal number (0-6).
%X The time representation in HH:MM:SS format.
%x The date representation in MM/DD/YY format.
%Y The year with century as a decimal number.
%y The year without century as a decimal number (00-99), with an optional leading zero. Can be mixed with %C. If %C is not specified, years 00-68 are 2000s, while years 69-99 are 1900s.
%Z The time zone name.
%z The offset from the Prime Meridian in the format +HHMM or -HHMM as appropriate, with positive values representing locations east of Greenwich.
%% A single % character.
%Ez RFC 3339-compatible numeric time zone (+HH:MM or -HH:MM).
%E#S Seconds with # digits of fractional precision.
%E*S Seconds with full fractional precision (a literal '*').
%E4Y Four-character years (0001 ... 9999). Note that %Y produces as many characters as it takes to fully render the year.

Timezone definitions

Certain date and timestamp functions allow you to override the default time zone and specify a different one. You can specify a time zone by either supplying the time zone name (for example, America/Los_Angeles) or time zone offset from UTC (for example, -08).

If you choose to use a time zone offset, use this format:

(+|-)H[H][:M[M]]

The following timestamps are equivalent because the time zone offset for America/Los_Angeles is -08 for the specified date and time.

SELECT UNIX_MILLIS(TIMESTAMP "2008-12-25 15:30:00 America/Los_Angeles") as millis;

SELECT UNIX_MILLIS(TIMESTAMP "2008-12-25 15:30:00-08:00") as millis;