title: Suggestions for a user notification system in MySql and PHP
body: <p>I am implementing a notification system and seeing if these suggestions are valid to set up, if one is better than the other or a better solution is available:</p>
  
  <p>A notification is added to the database. A guest / identifiable user logs onto or uses the site. They are greeted with notifications they haven't seen before with the option to close or read later.</p>
  
  <ul>
  <li>Notification table stores notification texts and Id.</li>
  <li><strong>Option 1:</strong> Alerts table stores all users who have read the notification</li>
  <li><strong>Option 2:</strong> Alerts table stores all users who have NOT read the notification</li>
  </ul>
  
  <p>Are these options much of a muchness, is it better to add potentially 100,000+ alerts and as those users discard or interact with the notice, their status is changed or the alert deleted. This could become a very large table...</p>
  
  <p>What's a more extensible set up for custom notifications based on user activity?</p>