title: MySQL: NULL vs ""
body: <p>Is it better to use <code>default null</code> or <code>default ""</code> for text fields in MySQL?</p>
  
  <p>Why?</p>
  
  <p>Update: I know what means each of them. I am interested what is better to use considering disk space and performance.</p>
  
  <p>Update 2: Hey ppl! The question was "what is better to use" not "what each means" or "how to check them"...</p>