6.13. Date and Time Functions and Operators

Date and Time Operators

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).

• fromiso8601_timestamp(_string) → timestamp with time zone

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

• fromiso8601_date(_string) → date

• Parses the ISO 8601 formatted string into a date.

• fromunixtime(_unixtime) → timestamp

• Returns the UNIX timestamp unixtime as a timestamp.

• fromunixtime(_unixtime, string) → timestamp with time zone

• Returns the UNIX timestamp unixtime as a timestamp with time zoneusing string for the time zone.

• fromunixtime(_unixtime, hours, minutes) → timestamp with time zone

• Returns the UNIX timestamp unixtime as a timestamp with time zoneusing hours and minutes for the time zone offset.

• 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.

• toiso8601(_x) → varchar

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

• tomilliseconds(_interval) → bigint

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

• tounixtime(_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.

• datetrunc(_unit, x) → [same as input]
• Returns x truncated to unit.

Interval Functions

The functions in this section support the following interval units:

• dateadd(_unit, value, timestamp) → [same as input]

• Adds an interval value of type unit to timestamp.Subtraction can be performed by using a negative value.

• datediff(_unit, timestamp1, timestamp2) → bigint

• Returns timestamp2 - timestamp1 expressed in terms of unit.

Duration Function

The parse_duration function supports the following units:

• parseduration(_string) → interval
• Parses string of format value unit into an interval, wherevalue 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 withthe 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

• dateformat(_timestamp, format) → varchar

• Formats timestamp as a string using format.

• dateparse(_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 withJodaTime’s DateTimeFormat pattern format.

• formatdatetime(_timestamp, format) → varchar

• Formats timestamp as a string using format.

• parsedatetime(_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 thefield 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.

• dayof_month(_x) → bigint

• This is an alias for day().

• dayof_week(_x) → bigint

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

• dayof_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.

• timezonehour(_timestamp) → bigint

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

• timezoneminute(_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.

• weekof_year(_x) → bigint

• This is an alias for week().

• year(x) → bigint

• Returns the year from x.

• yearof_week(_x) → bigint

• Returns the year of the ISO week from x.

• yow(x) → bigint

• This is an alias for year_of_week().