title: Adding check constraints without "create assertion" in MYSQL
body: <p>I'm trying to add a check constraint to the tables ORDERS and RESULTS in my database, but MYSQL won't accept assertions. How do I edit this to fit MYSQL's accepted syntax? Can it be done with an ALTER TABLE?  </p>
  
  <pre><code>CREATE ASSERTION
  CHECK (NOT EXISTS SELECT * FROM ORDERS, RESULTS, 
  WHERE ORDERS.ORDER_NUMBER = RESULTS.ORDER_NUMBER 
  AND ORDERS.ORDER_DATE &gt; RESULTS.DATE_REPORTED);
  </code></pre>