As a newcomer to Sequel's ORM, it took me quite a while to figure out why this code would throw `method mimetype= doesn't exist (Sequel::Error)` on the `create` call.

sickwell.rb

require 'sequel'

DB = Sequel.sqlite 

DB.create_table :mimetype do 
    primary_key :id
    column :mimetype, :text, :unique=>true
    column :extension, :text
end

class Mimetype < Sequel::Model; end

Mimetype.create(:mimetype => 'text/bullshit', :extension => 'bs')

Long story short, this is because I did not pluralize the table name. Not the most helpful error message in this case.