Datetime

An ISO 8601 compliant date and time type.

Syntax

A datetime literal consists of a date fragment and a time fragment, separated by the character T.

The date fragment consists of the following values, separated by a -:

  • either a four-digit year or a sign with any number of digits for the year (e.g. +252525 meaning year 252525),

  • a two-digit month of the year,

  • and a two-digit day of that month.

The time fragment consists of the following values, separated by ::

  • a two-digit hour between 00 and 24,

  • a two-digit minute between 00 and 59,

  • a two-digit second between 00 and 59 with up to nine digits after the decimal point.

Example datetime literals
2024-03-30T12:00:00
1920-09-21T09:00:00

#!test[read]
#{{
match
    let $x = 2024-03-30T12:00:00;
    let $y = 1920-09-21T09:00:00;
#}}
Example datetime literals (non-4-digit year)
+20000-01-01T10:30:00.000
+900-09-21T19:59:59.358

#!test[read]
#{{
match
    let $x = +20000-01-01T10:30:00.000;
    let $y = +900-09-21T19:59:59.358;
#}}

In expressions

A difference between two datetime values is a duration such that when it is added to the earlier datetime, it produces the later datetime. See the Duration type reference for more information about datetime-duration arithmetic. The time portion of the result is always under 24 hours.

2024-03-30T12:00:00 - 2020-09-21T09:00:00 == P3Y6M9DT3H
2020-09-21T09:00:00 + P3Y6M9DT3H == 2024-03-30T12:00:00

Defining a datetime valued attribute

#!test[schema]
define
  attribute local-sunset value datetime;

Inserting a datetime valued attribute

#!test[write]
insert
  $_ isa local-sunset 2025-01-10T16:13;