Construct at least one trigger to either manage a constraint, a derived attribute, or create an audit trail. Update the database as necessary. Which (one) trigger you create and on which table is your choice, but in your submission explain why you built that trigger and what its intended purpose is. For example, you might enforce that a lesson is not included twice in the same course. Or a trigger that tracks all modifications to a lesson (of course, this will require modifications and additions to your databases).