title: Database record containing multiple entries in one column
body: <p>I am working on a web app written in rails. It is currently running on heroku with a postgres database.</p>
  
  <p>I am supposed to add a feature where users may enter <strong>up to three</strong> codes for each one of the user's students. The codes themselves are irrelevant, they are simply strings that will be entered into the database. </p>
  
  <p>This brings me to my dilemma. I am unsure of how to best store the codes in terms of their relationship to the student table. My original thought was to use the rails method <code>serialize</code> to store up to three codes in an array, but I have read that more often than not, storing data in an array in a database is not what you want to do. </p>
  
  <p>Should I create a new table "codes" and set up a <code>has_many</code> relationship with the "students" table? Or is there a more preferable away to set up this relationship?</p>