This is sequel extension makes using crosstab function more convenient
Installation
Add this line to your application's Gemfile:
gem 'sequel-tablefunc'And then execute:
$ bundle
Usage
Assuming you have table which already have 2 categories. This table can be represented as a pivot table
  User.select_group(:type_id, :status_id)
      .select_append(:count.sql_function('*'.lit))
      .order(:type_id)
      .crosstab(User.select(:status_id).distinct.order(:status_id))
      .all| row_name | status1 | status2 | 
|---|---|---|
| type1 | 5 | 10 | 
| type2 | 1 | 2 | 
It is easy, isn't it?
  User.select_group(:date_trunc.sql_function('year', :created_at), :status_id)
      .select_append(:count.sql_function('*'.lit))
      .order(:date_trunc.sql_function('year', :created_at))
      .crosstab(User.select(:status_id)
      .distinct
      .order(:status_id))
      .all| row_name | status1 | status2 | 
|---|---|---|
| 2012-01-01 00:00:00 | 6 | nil | 
| 2013-01-01 00:00:00 | nil | 12 | 
Development
After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.
To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.
Contributing
Bug reports and pull requests are welcome on GitHub at https://github.com/umbrellio/sequel-tablefunc.