续集会重复输入

Question

我正在使用Sequel与Sinatra并且我一直在尝试它并且我注意到它创建了重复的条目（3x）。我试图调试它但最后我不明白为什么会发生这种情况

这是我的代码：

require 'sinatra'
require 'mysql2'
require 'sequel'

 DB=Sequel.connect(
                      :adapter => "mysql2",
                      :host =>"localhost",
                      :user => "root",
                      :password => "",
                      :database => "test"
                      )
  if !DB.table_exists? :users 
    DB.create_table :users do
      primary_key :id
      String :username ,:size=>20 #,:unique=>true
      String :password ,:size=>30 
  end   
  puts "Schema created"
else
  puts "Already exists"
end

  class User < Sequel::Model;end





class Test < Sinatra::Base

  get '/:username' do   
    "Creating user"
    User.create(:username => "#{params['username']}",:password => "test")
  end
end