code: func (dm *DjangoMigration) Update(db XODB) error {
  	var err error
  
  	// if doesn't exist, bail
  	if !dm._exists {
  		return errors.New("update failed: does not exist")
  	}
  
  	// if deleted, bail
  	if dm._deleted {
  		return errors.New("update failed: marked for deletion")
  	}
  
  	// sql query
  	const sqlstr = `UPDATE django.django_migrations SET ` +
  		`app = :1, name = :2, applied = :3` +
  		` WHERE id = :4`
  
  	// run query
  	XOLog(sqlstr, dm.App, dm.Name, dm.Applied, dm.ID)
  	_, err = db.Exec(sqlstr, dm.App, dm.Name, dm.Applied, dm.ID)
  	return err
  }
docs: // Update updates the DjangoMigration in the database.