title: Add timestamps to existing table in db Rails 5+
body: <p>Trying to add Timestamps to existing table.
  According to <a href="https://apidock.com/rails/ActiveRecord/ConnectionAdapters/SchemaStatements/add_timestamps" rel="noreferrer">Api documenation add_timestamps</a></p>
  <p>Here is my code in migration:</p>
  <pre><code>  def change
      add_timestamps(:products, null: false)
    end
  </code></pre>
  <p>Getting error:</p>
  <pre><code>*-- add_timestamps(:products, {:null=&gt;false})
  rails aborted!
  StandardError: An error has occurred, this and all later migrations canceled:
  SQLite3::SQLException: Cannot add a NOT NULL column with default value NULL: ALTER TABLE &quot;products&quot; ADD &quot;created_at&quot; datetime NOT NULL*
  </code></pre>
  <p>I've also tried all solution in this <a href="https://stackoverflow.com/questions/7542976/add-timestamps-to-an-existing-table">thread</a></p>
  <p>Same error...
  Rails 5.1.4
  Ruby 2.4.0</p>