def insertDomain(self, domain, indegree=0, outdegree=0):
		'''增加一个域名'''
		cur = self.conn.cursor()
		cur.execute("INSERT INTO Domains VALUES (NULL,?,?,?)", (domain, indegree, outdegree))
		# 写入到文件中
		self.conn.commit()
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