title: MySQL add a NOT NULL column
body: <p>I am adding a column to a table:</p>
  
  <pre><code>ALTER TABLE t ADD c varchar(10) NOT NULL;
  </code></pre>
  
  <p>The column gets added, and each record has the empty string.</p>
  
  <p>Is this expected to work this way under all conditions (strict mode, etc.) in MySQL 5.5+?</p>