Interval Type
Version dev

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 substracting 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.

``````-- 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';

-- WARNING: If a decimal value is specified, it will be automatically truncated 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))
-- 1 year
SELECT INTERVAL '1.5' YEARS; --WARNING! This returns 1 year!
``````

## 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       │
│     interval     │
├──────────────────┤
│ 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  │
│ int64 │
├───────┤
│     1 │
└───────┘
``````

## Functions

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

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

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