def close(self):
		'''关闭与数据库的连接'''
		if VERBOSE:
			print 'Database connection CLOSE.'
		self.conn.close()
def get_primary_domain(self):
        """
        Returns the primary domain of the tenant
        """
        try:
            domain = self.domains.get(is_primary=True)
            return domain
        except get_tenant_domain_model().DoesNotExist:
            return None