Last Modified
  2013-07-26 17:20:49 +0000
Requires

## Description

The date_arithmetic extension adds the ability to perform database-independent addition/substraction of intervals to/from dates and timestamps.

First, you need to load the extension into the database:

    DB.extension :date_arithmetic

Then you can use the Sequel.date_add and Sequel.date_sub methods to return Sequel expressions:

    add = Sequel.date_add(:date_column, :years=>1, :months=>2, :days=>3)
    sub = Sequel.date_sub(:date_column, :hours=>1, :minutes=>2, :seconds=>3)

In addition to specifying the interval as a hash, there is also support for specifying the interval as an ActiveSupport::Duration object:

    require 'active_support/all'
    add = Sequel.date_add(:date_column, 1.years + 2.months + 3.days)
    sub = Sequel.date_sub(:date_column, 1.hours + 2.minutes + 3.seconds)

These expressions can be used in your datasets, or anywhere else that Sequel expressions are allowed:

    DB[:table].select(add.as(:d)).where(sub > Sequel::CURRENT_TIMESTAMP)