title: When to use nullable columns - sql
body: <p>In specs default columns are set as nullable meaning they optional, I'm not clear what scenario is this good for to use with? I'll break it into two questions:</p>
  
  <ol>
  <li><p>Why would I even want to use it in relational db? If integrity isn't important Ill use other half-structured model. Fearing for each row would it return usable object. Seems it is pretty rare scenario to use them in relational db.</p></li>
  <li><p>Handling it in programing language. Is it even different in different languages? Let's say php, what values should it be compared with? fetch_array() are even keys going to be set?</p></li>
  </ol>