This section describes functions and operators for examining and manipulating INTERVAL values.

Interval Operators

The table below shows the available mathematical operators for INTERVAL types.

Operator	Description	Example	Result
+	addition of an INTERVAL	INTERVAL 1 HOUR + INTERVAL 5 HOUR	INTERVAL 6 HOUR
+	addition to a DATE	DATE '1992-03-22' + INTERVAL 5 DAY	1992-03-27
+	addition to a TIMESTAMP	TIMESTAMP '1992-03-22 01:02:03' + INTERVAL 5 DAY	1992-03-27 01:02:03
+	addition to a TIME	TIME '01:02:03' + INTERVAL 5 HOUR	06:02:03
-	subtraction of an INTERVAL	INTERVAL 5 HOUR - INTERVAL 1 HOUR	INTERVAL 4 HOUR
-	subtraction from a DATE	DATE '1992-03-27' - INTERVAL 5 DAY	1992-03-22
-	subtraction from a TIMESTAMP	TIMESTAMP '1992-03-27 01:02:03' - INTERVAL 5 DAY	1992-03-22 01:02:03
-	subtraction from a TIME	TIME '06:02:03' - INTERVAL 5 HOUR	01:02:03

Interval Functions

The table below shows the available scalar functions for INTERVAL types.

Function	Description	Example	Result
date_part(part, interval)	Get subfield (equivalent to extract)	date_part('year', INTERVAL '14 months')	1
datepart(part, interval)	Alias of date_part. Get subfield (equivalent to extract)	datepart('year', INTERVAL '14 months')	1
extract(part from interval)	Get subfield from a date	extract('month' FROM INTERVAL '14 months')	2
to_days(integer)	Construct a day interval	to_days(5)	INTERVAL 5 DAY
to_hours(integer)	Construct a hour interval	to_hours(5)	INTERVAL 5 HOUR
to_microseconds(integer)	Construct a microsecond interval	to_microseconds(5)	INTERVAL 5 MICROSECOND
to_milliseconds(integer)	Construct a millisecond interval	to_milliseconds(5)	INTERVAL 5 MILLISECOND
to_minutes(integer)	Construct a minute interval	to_minutes(5)	INTERVAL 5 MINUTE
to_months(integer)	Construct a month interval	to_months(5)	INTERVAL 5 MONTH
to_seconds(integer)	Construct a second interval	to_seconds(5)	INTERVAL 5 SECOND
to_years(integer)	Construct a year interval	to_years(5)	INTERVAL 5 YEAR

Only the documented date parts are defined for intervals.