title: MySql workbench CHECK constraint
body: <p>Here I want to create 2 CHECK constraint before the record insert to the database.</p>
  
  <pre><code>ALTER TABLE SubjectEnrollment
  ADD CONSTRAINT register CHECK (register &lt;= classSize AND register &gt;=0),
  ADD CONSTRAINT available CHECK (available &lt;= classSize AND available &gt;= 0);
  </code></pre>
  
  <ol>
  <li>register attribute should not more than classSize attribute and less than 0. </li>
  <li>available attribute should not more than classSize attribte and less than 0.</li>
  </ol>
  
  <p>When I type in this syntax in MySql Workbench, it complaints "Syntax Error: unexpected 'CHECK' (check)'. How should I add these, using TRIGGER?</p>
  
  <p>Thank you.</p>