DateTime arithmetic in an ActiveRecord query (PostgreSQL)
activerecord, postgresql, rails-activerecord, ruby-on-rails, ruby-on-rails-3
Solution
The easiest way to do this is to use an interval, then it is pretty much a straight transliteration of the Rails version:
User.where(%q{created_at - birthdate < interval '13 years'})
The difference between two timestamps (or a timestamp and a date) is an interval so you just need the appropriate value on the right side of your comparison.
Problem
I have two `datetime` columns in a `User`/`users` table: `created_at` and `birthdate`. I'd like to find users whose birthdate is less than 13 years before their creation date. The equivalent Rails `if` statement would be `((created_at - birthdate) < 13.years)` How do I translate this to an ActiveRecord query (one that'll work on PostgreSQL)? Is this even possible, or will I have to iterate over all records manually?