title: SQL column which is a list containing other rows
body: <p>I have a table which looks like this:</p>
  
  <p><strong>Persons</strong></p>
  
  <pre><code>| Id | Name | FavoriteColor |
  </code></pre>
  
  <p>And I want to add a new column which is "Friends" so that it becomes</p>
  
  <p><strong>Persons</strong></p>
  
  <pre><code>| Id | Name | FavoriteColor | Friends |
  </code></pre>
  
  <p>I want the <code>Friends</code> column to be (in abstraction) a list containing the Ids of other rows in the <code>Persons</code> table.</p>
  
  <p>What's the best way to do this? I know I can use FK's to link up tables, but I'm not just linking a specific row to a specific row in a different table, but rather a specific row to a specific table.</p>