title: reseting primary key id in rails
body: <p>I am having problem with how the primary key gets incremented when I delete_all from a table and start inserting again. This is problematic because I have other models that are associated with the purged table. For example, if I have Apple that belongs_to Computer, then when I purge the Computer table and re-add the computer, the associations get messed up because Apple now has infant computer_id in its rows. I want to be able to reset the primary key of the computer so that when I re-add the computer, the association still stays intact. How should I go about doing this in rails?</p>
  
  <p><strong>Edit</strong>
  I am very sorry for not being clear about this, but now I will tell you want I want to do. I want a user to be associated with a machine (computer). A computer has his own id and can only be created by the admin. There are a fixed amount of computer in the computer table.</p>
  
  <pre><code>User
  belongs_to :computer
  
  Computer
  has_many :users
  </code></pre>
  
  <p>The problem that I am facing is that, I have the computer table pre-loaded inside seeds.rb/some rakefile. When I start up my app, I want to just run the file that first deletes everything and then pre-loads the table. This will let the user choose a computer only from the ones provided in the computer table. I want to be able to run this script again (say in heroku console, without dropping the User table) and still get the same id associated to each machine (and thus to each user). I am confused on how I should do this. Please let me know if I should do this differently.</p>