# Presto 316 Documentation

## 7.13. Date and Time Functions and Operators

## Date and Time Operators

Operator | Example | Result
--- | --- | ---
`+` | `date '2012-08-08' + interval '2' day` | `2012-08-10`
`+` | `time '01:00' + interval '3' hour` | `04:00:00.000`
`+` | `timestamp '2012-08-08 01:00' + interval '29' hour` | `2012-08-09 06:00:00.000`
`+` | `timestamp '2012-10-31 01:00' + interval '1' month` | `2012-11-30 01:00:00.000`
`+` | `interval '2' day + interval '3' hour` | `2 03:00:00.000`
`+` | `interval '3' year + interval '5' month` | `3-5`
`-` | `date '2012-08-08' - interval '2' day` | `2012-08-06`
`-` | `time '01:00' - interval '3' hour` | `22:00:00.000`
`-` | `timestamp '2012-08-08 01:00' - interval '29' hour` | `2012-08-06 20:00:00.000`
`-` | `timestamp '2012-10-31 01:00' - interval '1' month` | `2012-09-30 01:00:00.000`
`-` | `interval '2' day - interval '3' hour` | `1 21:00:00.000`
`-` | `interval '3' year - interval '5' month` | `2-7`

## 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

## Date and Time Functions

`current_date -> date`

  Returns the current date as of the start of the query.

`current_time -> time with time zone`

  Returns the current time as of the start of the query.

`current_timestamp -> timestamp with time zone`

  Returns the current timestamp as of the start of the query.

`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`)

`date`(x) → date

  This is an alias for `CAST(x AS date)`.

`from_iso8601_timestamp`(string) → timestamp with time zone

  Parses the ISO 8601 formatted `string` into a `timestamp with time zone`.

`from_iso8601_date`(string) → date

  Parses the ISO 8601 formatted `string` into a `date`.

`from_unixtime`(unixtime) → timestamp

  Returns the UNIX timestamp `unixtime` as a timestamp. `unixtime` is the number of seconds since `1970-01-01 00:00:00`.

`from_unixtime`(unixtime, string) → timestamp with time zone

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

`from_unixtime`(unixtime, hours, minutes) → timestamp with time zone

  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`.

`localtime -> time`

  Returns the current time as of the start of the query.

`localtimestamp -> timestamp`

  Returns the current timestamp as of the start of the query.

`now`() → timestamp with time zone

  This is an alias for `current_timestamp`.

`to_iso8601`(x) → varchar

  Formats `x` as an ISO 8601 string. `x` can be date, timestamp, or timestamp with time zone.

`to_milliseconds`(interval) → bigint

  Returns the day-to-second `interval` as milliseconds.

`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:

Unit | Example Truncated Value
--- | ---
`second` | `2001-08-22 03:04:05.000`
`minute` | `2001-08-22 03:04:00.000`
`hour` | `2001-08-22 03:00:00.000`
`day` | `2001-08-22 00:00:00.000`
`week` | `2001-08-20 00:00:00.000`
`month` | `2001-08-01 00:00:00.000`
`quarter` | `2001-07-01 00:00:00.000`
`year` | `2001-01-01 00:00:00.000`

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

`date_trunc`(unit, x) → [same as input]

  Returns `x` truncated to `unit`.

## Interval Functions

The functions in this section support the following interval units:

Unit | Description
--- | ---
`millisecond` | Milliseconds
`second` | Seconds
`minute` | Minutes
`hour` | Hours
`day` | Days
`week` | Weeks
`month` | Months
`quarter` | Quarters of a year
`year` | Years

`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.

`date_diff`(unit, timestamp1, timestamp2) → bigint

  Returns `timestamp2 - timestamp1` expressed in terms of `unit`.

## Duration Function

The `parse_duration` function supports the following units:

Unit | Description
--- | ---
`ns` | Nanoseconds
`us` | Microseconds
`ms` | Milliseconds
`s` | Seconds
`m` | Minutes
`h` | Hours
`d` | Days

`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

## 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:

Specifier | Description
--- | ---
`%a` | Abbreviated weekday name (`Sun` .. `Sat`)
`%b` | Abbreviated month name (`Jan` .. `Dec`)
`%c` | Month, numeric (`1` .. `12`) [4]
`%D` | Day of the month with English suffix (`0th`, `1st`, `2nd`, `3rd`, …)
`%d` | Day of the month, numeric (`01` .. `31`) [4]
`%e` | Day of the month, numeric (`1` .. `31`) [4]
`%f` | Fraction of second (6 digits for printing: `000000` .. `999000`; 1 - 9 digits for parsing: `0` .. `999999999`) [1]
`%H` | Hour (`00` .. `23`)
`%h` | Hour (`01` .. `12`)
`%I` | Hour (`01` .. `12`)
`%i` | Minutes, numeric (`00` .. `59`)
`%j` | Day of year (`001` .. `366`)
`%k` | Hour (`0` .. `23`)
`%l` | Hour (`1` .. `12`)
`%M` | Month name (`January` .. `December`)
`%m` | Month, numeric (`01` .. `12`) [4]
`%p` | `AM` or `PM`
`%r` | Time, 12-hour (`hh:mm:ss` followed by `AM` or `PM`)
`%S` | Seconds (`00` .. `59`)
`%s` | Seconds (`00` .. `59`)
`%T` | Time, 24-hour (`hh:mm:ss`)
`%U` | Week (`00` .. `53`), where Sunday is the first day of the week
`%u` | Week (`00` .. `53`), where Monday is the first day of the week
`%V` | Week (`01` .. `53`), where Sunday is the first day of the week; used with `%X`
`%v` | Week (`01` .. `53`), where Monday is the first day of the week; used with `%x`
`%W` | Weekday name (`Sunday` .. `Saturday`)
`%w` | Day of the week (`0` .. `6`), where Sunday is the first day of the week [3]
`%X` | Year for the week where Sunday is the first day of the week, numeric, four digits; used with `%V`
`%x` | Year for the week, where Monday is the first day of the week, numeric, four digits; used with `%v`
`%Y` | Year, numeric, four digits
`%y` | Year, numeric (two digits) [2]
`%%` | A literal `%` character
`%x` | `x`, for any `x` not listed above

[1] | Timestamp is truncated to milliseconds.

[2] | When parsing, two-digit year format assumes range `1970` .. `2069`, so “70” will result in year `1970` but “69” will produce `2069`.

[3] | This specifier is not supported yet. Consider using `day_of_week()` (it uses `1-7` instead of `0-6`).

[4] | (1, 2, 3, 4) This specifier does not support `0` as a month or day.

Warning

The following specifiers are not currently supported: `%D %U %u %V %w %X`

`date_format`(timestamp, format) → varchar

  Formats `timestamp` as a string using `format`.

`date_parse`(string, format) → timestamp

  Parses `string` into a timestamp using `format`.

## Java Date Functions

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

`format_datetime`(timestamp, format) → varchar

  Formats `timestamp` as a string using `format`.

`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:

Field | Description
--- | ---
`YEAR` | `year()`
`QUARTER` | `quarter()`
`MONTH` | `month()`
`WEEK` | `week()`
`DAY` | `day()`
`DAY_OF_MONTH` | `day()`
`DAY_OF_WEEK` | `day_of_week()`
`DOW` | `day_of_week()`
`DAY_OF_YEAR` | `day_of_year()`
`DOY` | `day_of_year()`
`YEAR_OF_WEEK` | `year_of_week()`
`YOW` | `year_of_week()`
`HOUR` | `hour()`
`MINUTE` | `minute()`
`SECOND` | `second()`
`TIMEZONE_HOUR` | `timezone_hour()`
`TIMEZONE_MINUTE` | `timezone_minute()`

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

`extract`(field FROM x) → bigint

  Returns `field` from `x`.

  Note

  This SQL-standard function uses special syntax for specifying the arguments.

## Convenience Extraction Functions

`day`(x) → bigint

  Returns the day of the month from `x`.

`day_of_month`(x) → bigint

  This is an alias for `day()`.

`day_of_week`(x) → bigint

  Returns the ISO day of the week from `x`. The value ranges from `1` (Monday) to `7` (Sunday).

`day_of_year`(x) → bigint

  Returns the day of the year from `x`. The value ranges from `1` to `366`.

`dow`(x) → bigint

  This is an alias for `day_of_week()`.

`doy`(x) → bigint

  This is an alias for `day_of_year()`.

`hour`(x) → bigint

  Returns the hour of the day from `x`. The value ranges from `0` to `23`.

`millisecond`(x) → bigint

  Returns the millisecond of the second from `x`.

`minute`(x) → bigint

  Returns the minute of the hour from `x`.

`month`(x) → bigint

  Returns the month of the year from `x`.

`quarter`(x) → bigint

  Returns the quarter of the year from `x`. The value ranges from `1` to `4`.

`second`(x) → bigint

  Returns the second of the minute from `x`.

`timezone_hour`(timestamp) → bigint

  Returns the hour of the time zone offset from `timestamp`.

`timezone_minute`(timestamp) → bigint

  Returns the minute of the time zone offset from `timestamp`.

`week`(x) → bigint

  Returns the ISO week of the year from `x`. The value ranges from `1` to `53`.

`week_of_year`(x) → bigint

  This is an alias for `week()`.

`year`(x) → bigint

  Returns the year from `x`.

`year_of_week`(x) → bigint

  Returns the year of the ISO week from `x`.

`yow`(x) → bigint

  This is an alias for `year_of_week()`.