How to see MySQL queries in rails console [duplicate]

This question already has answers here: How to show SQL queries run in the Rails console? (8 answers) Closed 8 years ago.

Is there a开发者_如何学编程 way to see which MySQL queries are fired from ActiveRecord in the rails console?

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Yes, this can be achieved through redirecting rails log to standard output.

Write these in your console prompt:

ActiveRecord::Base.logger = Logger.new(STDOUT)
ActiveRecord::Base.connection_pool.clear_reloadable_connections!

Furthermore, you can put these lines in ~/.irbrc file, so that each time you don't need to manually write these 2 lines:

require 'rubygems'

if ENV.include?('RAILS_ENV') && ENV["RAILS_ENV"] == 'development'
    ActiveRecord::Base.logger = Logger.new(STDOUT)
    ActiveRecord::Base.connection_pool.clear_reloadable_connections!
end

Hope this helps...

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In Rails 3+ you can use ActiveRecord::Relation’s to_sql method:

User.where(:id => 3).to_sql
#=> "SELECT \"users\".* FROM \"users\"  WHERE \"users\".\"id\" = 3"

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Another way to do it for each project is inspired by http://guides.rubyonrails.org/debugging_rails_applications.html#what-is-the-logger-questionmark:

You can specify an alternative logger in your environment.rb or any environment file:

ActiveRecord::Base.logger = Logger.new("log/active_record.log") #This outputs the mysql queries to a file named active_record.log under your project's log folder.

Of course, you need to restart your server to make things work.