pqからsqlite3への切り替えruby on rails

Question

pgからsqlite3に変更しようとするとエラーが発生します。

rake db:reset 
rake aborted! 
Gem::LoadError: Specified 'postgresql' for database adapter, but the gem is not loaded. Add `gem 'pg'` to your Gemfile (and ensure its version is at the minimum required by ActiveRecord). 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/lib/active_record/connection_adapters/connection_specification.rb:177:in `rescue in spec' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/lib/active_record/connection_adapters/connection_specification.rb:174:in `spec' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/lib/active_record/connection_handling.rb:50:in `establish_connection' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/lib/active_record/railtie.rb:120:in `block (2 levels) in <class:Railtie>' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activesupport-4.2.5/lib/active_support/lazy_load_hooks.rb:38:in `instance_eval' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activesupport-4.2.5/lib/active_support/lazy_load_hooks.rb:38:in `execute_hook' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activesupport-4.2.5/lib/active_support/lazy_load_hooks.rb:28:in `block in on_load' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activesupport-4.2.5/lib/active_support/lazy_load_hooks.rb:27:in `each' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activesupport-4.2.5/lib/active_support/lazy_load_hooks.rb:27:in `on_load' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/lib/active_record/railtie.rb:116:in `block in <class:Railtie>' 
/usr/local/rvm/gems/ruby-2.3.0/gems/railties-4.2.5/lib/rails/initializable.rb:30:in `instance_exec' 
/usr/local/rvm/gems/ruby-2.3.0/gems/railties-4.2.5/lib/rails/initializable.rb:30:in `run' 
/usr/local/rvm/gems/ruby-2.3.0/gems/railties-4.2.5/lib/rails/initializable.rb:55:in `block in run_initializers' 
/usr/local/rvm/gems/ruby-2.3.0/gems/railties-4.2.5/lib/rails/initializable.rb:54:in `run_initializers' 
/usr/local/rvm/gems/ruby-2.3.0/gems/railties-4.2.5/lib/rails/application.rb:352:in `initialize!' 
/home/ubuntu/workspace/config/environment.rb:5:in `<top (required)>' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activesupport-4.2.5/lib/active_support/dependencies.rb:274:in `require' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activesupport-4.2.5/lib/active_support/dependencies.rb:274:in `block in require' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activesupport-4.2.5/lib/active_support/dependencies.rb:240:in `load_dependency' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activesupport-4.2.5/lib/active_support/dependencies.rb:274:in `require' 
/usr/local/rvm/gems/ruby-2.3.0/gems/railties-4.2.5/lib/rails/application.rb:328:in `require_environment!' 
/usr/local/rvm/gems/ruby-2.3.0/gems/railties-4.2.5/lib/rails/application.rb:457:in `block in run_tasks_blocks' 
/usr/local/rvm/gems/ruby-2.3.0/gems/rake-12.0.0/exe/rake:27:in `<top (required)>' 
/usr/local/rvm/gems/ruby-2.3.0/bin/ruby_executable_hooks:15:in `eval' 
/usr/local/rvm/gems/ruby-2.3.0/bin/ruby_executable_hooks:15:in `<main>' 
Gem::LoadError: pg is not part of the bundle. Add it to your Gemfile. 
/usr/local/rvm/gems/ruby-2.3.0/gems/bundler-1.15.1/lib/bundler/rubygems_integration.rb:377:in `block (2 levels) in replace_gem' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/lib/active_record/connection_adapters/postgresql_adapter.rb:16:in `<top (required)>' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activesupport-4.2.5/lib/active_support/dependencies.rb:274:in `require' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activesupport-4.2.5/lib/active_support/dependencies.rb:274:in `block in require' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activesupport-4.2.5/lib/active_support/dependencies.rb:240:in `load_dependency' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activesupport-4.2.5/lib/active_support/dependencies.rb:274:in `require' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/lib/active_record/connection_adapters/connection_specification.rb:175:in `spec' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/lib/active_record/connection_handling.rb:50:in `establish_connection' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/lib/active_record/railtie.rb:120:in `block (2 levels) in <class:Railtie>' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activesupport-4.2.5/lib/active_support/lazy_load_hooks.rb:38:in `instance_eval' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activesupport-4.2.5/lib/active_support/lazy_load_hooks.rb:38:in `execute_hook' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activesupport-4.2.5/lib/active_support/lazy_load_hooks.rb:28:in `block in on_load' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activesupport-4.2.5/lib/active_support/lazy_load_hooks.rb:27:in `each' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activesupport-4.2.5/lib/active_support/lazy_load_hooks.rb:27:in `on_load' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/lib/active_record/railtie.rb:116:in `block in <class:Railtie>' 
/usr/local/rvm/gems/ruby-2.3.0/gems/railties-4.2.5/lib/rails/initializable.rb:30:in `instance_exec' 
/usr/local/rvm/gems/ruby-2.3.0/gems/railties-4.2.5/lib/rails/initializable.rb:30:in `run' 
/usr/local/rvm/gems/ruby-2.3.0/gems/railties-4.2.5/lib/rails/initializable.rb:55:in `block in run_initializers' 
/usr/local/rvm/gems/ruby-2.3.0/gems/railties-4.2.5/lib/rails/initializable.rb:54:in `run_initializers' 
/usr/local/rvm/gems/ruby-2.3.0/gems/railties-4.2.5/lib/rails/application.rb:352:in `initialize!' 
/home/ubuntu/workspace/config/environment.rb:5:in `<top (required)>' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activesupport-4.2.5/lib/active_support/dependencies.rb:274:in `require' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activesupport-4.2.5/lib/active_support/dependencies.rb:274:in `block in require' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activesupport-4.2.5/lib/active_support/dependencies.rb:240:in `load_dependency' 
/usr/local/rvm/gems/ruby-2.3.0/gems/activesupport-4.2.5/lib/active_support/dependencies.rb:274:in `require' 
/usr/local/rvm/gems/ruby-2.3.0/gems/railties-4.2.5/lib/rails/application.rb:328:in `require_environment!' 
/usr/local/rvm/gems/ruby-2.3.0/gems/railties-4.2.5/lib/rails/application.rb:457:in `block in run_tasks_blocks' 
/usr/local/rvm/gems/ruby-2.3.0/gems/rake-12.0.0/exe/rake:27:in `<top (required)>' 
/usr/local/rvm/gems/ruby-2.3.0/bin/ruby_executable_hooks:15:in `eval' 
/usr/local/rvm/gems/ruby-2.3.0/bin/ruby_executable_hooks:15:in `<main>' 
Tasks: TOP => db:reset => environment 
(See full trace by running task with --trace) 

は、今私はActiveRecordのは、PGの宝石を追加するために私に言っているが、私のマシンではなく、その後に生産され、それを固定（PQサーバを実行して、エラーをしていることを知って、私はsqliteの上に置くしようとすることで怠けていますよデベをして製品につないでください）

これを解決する方法は？

Answer 1

adapterをconfig/database.ymlに変更してください。postgresqlからsqlite3に変更してください。

助けが必要です。