mysqldump data is not stored just structure is copied

I wrote a rake task to delete data from main table and dumping it another table and also creating sql file and deleting data from main table.

All works except data is not pushed into .sql file, it just has the structure of the table. I don't know were I am going wrong. Any suggestions or help on this. Thanks in advance

namespace :db do
require 'json'
desc "Add two days back data to drls_wk12 and delete from drls"
task :drl_2days_task => :environment do
    ActiveRecord::Base.transaction do
        begin
            back_date = (Date.today - 4).strftime("%Y-%m-%d")
            output_file = File.join("/root/drl_backups/", "#{back_date}.sql")
            #ActiveRecord::Base.connection.execute("TRUNCATE TABLE drls_wk12")
            ActiveRecord::Base.connection.execute("insert into drls_wk12 select * from drls where day = '#{back_date}'")
            system("/usr/bin/env mysqldump -u root test drls --where='day=#{back_date}' > #{output_file}")
            ActiveRecord::Base.connection.execute("DELETE FROM drls WHERE day = '#{back_date}'")
        rescue Exception => e
            ActiveRecord::Rollback
            puts "errors #{e.message}"
            #logger.warn("errors #{e.message}")
        end
    end
end 

end