title: Can't create foreign key with ON DELETE SET DEFAULT
body: <p>I can't create foreign keys with <code>ON DELETE SET DEFAULT</code>, but if i use <code>ON DELETE CASCADE</code> then all works here is my sql</p>
  
  <pre><code>CREATE TABLE person(  
      customer_id INT AUTO_INCREMENT PRIMARY KEY,  
      name VARCHAR(100) UNIQUE 
  );
  
  
  CREATE TABLE habits(  
      customer_id INT AUTO_INCREMENT PRIMARY KEY,  
      habit VARCHAR(100) UNIQUE 
  );
  
  INSERT INTO `test`.`habits` (`customer_id`, `habit`) VALUES (NULL, 'smoking'), (NULL, 'drinking');
  INSERT INTO `test`.`person` (`customer_id`, `name`) VALUES (NULL, 'John'), (NULL, 'Steve');
  
  CREATE TABLE foreigner(  
      customer_id INT AUTO_INCREMENT PRIMARY KEY,  
      customer VARCHAR(100) DEFAULT 'John', 
      habbit  VARCHAR(100) DEFAULT 'smoking', 
      FOREIGN KEY (customer) REFERENCES person(name)  ON DELETE SET DEFAULT ON UPDATE CASCADE,
      FOREIGN KEY (habbit) REFERENCES habits(habit)  ON DELETE SET DEFAULT ON UPDATE CASCADE     
  );
  </code></pre>
  
  <p>It's strange that it works if I use <code>ON DELETE CASCADE</code>.... any thoughts?</p>