# Specifying Interval Input

Interval values are expressed through interval literals. An interval literal is composed of one or more interval fields, where each field represents a span of days and time, or years and months, as follows:

`[-] { quantity subtype-unit }[…] [AGO]`

## Using Subtype Units

Subtype units are optional for day-time intervals; they must be specified for year-month intervals.

For example, the first statement below implicitly specifies days and time; the second statement explicitly identifies day and time units. Both statements return the same result:

=> SET INTERVALSTYLE TO UNITS; => SELECT INTERVAL '1 12:59:10:05'; ?column? -------------------- 1 day 12:59:10.005 (1 row)

=> SELECT INTERVAL '1 day 12 hours 59 min 10 sec 5 milliseconds'; ?column? -------------------- 1 day 12:59:10.005 (1 row)

The following two statements add 28 days and 4 weeks to the current date, respectively. The intervals in both cases are equal and the statements return the same result. However, in the first statement, the interval literal omits the subtype (implicitly `days`

); in the second statement, the interval literal must include the subtype unit `weeks`

:

=> SELECT CURRENT_DATE; ?column? ------------ 2016-08-15 (1 row) => SELECT CURRENT_DATE + INTERVAL '28'; ?column? --------------------- 2016-09-12 00:00:00 (1 row) dbadmin=> SELECT CURRENT_DATE + INTERVAL '4 weeks'; ?column? --------------------- 2016-09-12 00:00:00 (1 row)

An interval literal can include day-time and year-month fields. For example, the following statement adds an interval of 4 years, 4 weeks, 4 days and 14 hours to the current date. The years and weeks fields must include subtype units; the days and hours fields omit them:

> SELECT CURRENT_DATE + INTERVAL '4 years 4 weeks 4 14'; ?column? --------------------- 2020-09-15 14:00:00 (1 row)

## Omitting Subtype Units

You can specify quantities of days, hours, minutes, and seconds without specifying units. Vertica recognizes colons in interval literals as part of the timestamp:

=> SELECT INTERVAL '1 4 5 6'; ?column? ------------ 1 day 04:05:06 => SELECT INTERVAL '1 4:5:6'; ?column? ------------ 1 day 04:05:06 => SELECT INTERVAL '1 day 4 hour 5 min 6 sec'; ?column? ------------ 1 day 04:05:06

If Vertica cannot determine the units, it applies the quantity to any missing units based on the interval qualifier. In the next two examples, Vertica uses the default interval qualifier (`DAY TO SECOND(6)`

) and assigns the trailing `1`

to days, since it has already processed hours, minutes, and seconds in the output:

=> SELECT INTERVAL '4:5:6 1'; ?column? ------------ 1 day 04:05:06 => SELECT INTERVAL '1 4:5:6'; ?column? ------------ 1 day 04:05:06

In the next two examples, Vertica recognizes `4:5`

as `hours:minutes`

. The remaining values in the interval literal are assigned to the missing units: `1`

is assigned to days and `2`

is assigned to seconds.

SELECT INTERVAL '4:5 1 2'; ?column? ------------ 1 day 04:05:02 => SELECT INTERVAL '1 4:5 2'; ?column? ------------ 1 day 04:05:02

Specifying the interval qualifier can change how Vertica interprets `4:5`

:

=> SELECT INTERVAL '4:5' MINUTE TO SECOND; ?column? ------------ 00:04:05