Interval Values

An interval value represents the duration between two points in time.

Syntax

[ @ ] quantity unit [ quantity unit... ] [ AGO ]

Semantics


`@`	(at sign) is optional and ignored
quantity	is an integer numeric constant
unit	is one of the following units or abbreviations or plurals of the following units:
	SECOND MINUTE HOUR DAY WEEK	MONTH YEAR DECADE CENTURY MILLENNIUM
AGO	(optional) specifies a negative interval value (an interval going back in time)

The amounts of different units are implicitly added up with appropriate sign accounting.

Notes

Quantities of days, hours, minutes, and seconds can be specified without explicit unit markings. For example:
'1 12:59:10' is read the same as '1 day 12 hours 59 min 10 sec'
The boundaries of an interval constant are:
- '9223372036854775807 usec' to '9223372036854775807 usec ago'
- 296533 years 3 mons 21 days 04:00:54.775807 to -296533 years -3 mons -21 days -04:00:54.775807
The range of an interval constant is +/- 2⁶³ - 1 (plus or minus two to the sixty-third minus one) microseconds.

Examples

=> SELECT TIMESTAMP 'Apr 1, 07' - TIMESTAMP 'Mar 1, 07';

?column?

----------

1 mon

(1 row)

=> SELECT TIMESTAMP 'Mar 1, 07' - TIMESTAMP 'Feb 1, 07';

?column?

----------

1 mon

(1 row)

=> SELECT TIMESTAMP 'Feb 1, 07' + INTERVAL '30 days';

?column?

---------------------

2007-03-01 00:00:00

(1 row)