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Interval Type

Intervals represent a period of time. This period can be measured in a specific unit or combination of units, for example years, days, or seconds. Intervals are generally used to modify timestamps or dates by either adding or subtracting them.

Name Description
INTERVAL Period of time

An INTERVAL can be constructed by providing an amount together with a unit. Intervals can be added or subtracted from DATE or TIMESTAMP values.

Examples

1 year:

SELECT INTERVAL 1 YEAR;

Add 1 year to a specific date:

SELECT DATE '2000-01-01' + INTERVAL 1 YEAR;

Subtract 1 year from a specific date:

SELECT DATE '2000-01-01' - INTERVAL 1 YEAR;

Construct an interval from a column, instead of a constant:

SELECT INTERVAL (i) YEAR FROM range(1, 5) t(i);

Construct an interval with mixed units:

SELECT INTERVAL '1 month 1 day';

Intervals greater than 24 hours/12 months/etc. are supported:

SELECT '540:58:47.210'::INTERVAL;
SELECT INTERVAL '16 MONTHS';

Warning If a decimal value is specified, it will be automatically rounded to an integer. To use more precise values, simply use a more granular date part In this example, use 18 MONTHS instead of 1.5 YEARS. The statement below is equivalent to to_years(CAST(1.5 AS INTEGER))

SELECT INTERVAL '1.5' YEARS; -- WARNING! This returns 2 years!

Details

The interval class represents a period of time using three distinct components: the month, day and microsecond. These three components are required because there is no direct translation between them. For example, a month does not correspond to a fixed amount of days. That depends on which month is referenced. February has fewer days than March.

The division into components makes the interval class suitable for adding or subtracting specific time units to a date. For example, we can generate a table with the first day of every month using the following SQL query:

SELECT DATE '2000-01-01' + INTERVAL (i) MONTH
FROM range(12) t(i);

Difference between Dates

If we subtract two timestamps from one another, we obtain an interval describing the difference between the timestamps with the days and microseconds components. For example:

SELECT TIMESTAMP '2000-02-01 12:00:00' - TIMESTAMP '2000-01-01 11:00:00' AS diff;
diff
31 days 01:00:00

The datediff function can be used to obtain the difference between two dates for a specific unit.

SELECT datediff('month', TIMESTAMP '2000-01-01 11:00:00', TIMESTAMP '2000-02-01 12:00:00') AS diff;
diff
1

Functions

See the Date Part Functions page for a list of available date parts for use with an INTERVAL.

See the Interval Operators page for functions that operate on intervals.

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