def insertWebsite(self, url, domain):
		'''增加一个网页,标记为未访问,并对相应的domain增加其入度'''
		cur = self.conn.cursor()
		cur.execute("SELECT 1 FROM Domains WHERE domain=?", (domain,))
		result = cur.fetchone()
		if not result:
			# 未有对应domain记录, 先创建domain, 把入度设为1
			if VERBOSE:
				print 'Spot Domain:',domain
			self.insertDomain(domain, indegree=1)
			cur.execute("SELECT did FROM Domains WHERE domain=?", (domain,))
			did = cur.fetchone()[0]
		else:
			did = result[0]
			# 对应的domain记录已经存在, 对其入度+1
			cur.execute("UPDATE Domains SET outdegree=outdegree+1 WHERE domain=?", (domain,))

		cur.execute("INSERT INTO Websites VALUES (NULL,?,?,NULL,0)", (did, url,))
		# 写入到文件
		self.conn.commit()
def from_envvar(self, variable_name: str, silent: bool = False) -> bool:
        """Loads a configuration from an environment variable pointing to
        a configuration file.  This is basically just a shortcut with nicer
        error messages for this line of code::

            app.config.from_pyfile(os.environ['YOURAPPLICATION_SETTINGS'])

        :param variable_name: name of the environment variable
        :param silent: set to ``True`` if you want silent failure for missing
                       files.
        :return: bool. ``True`` if able to load config, ``False`` otherwise.
        """
        rv = os.environ.get(variable_name)
        if not rv:
            if silent:
                return False
            raise RuntimeError(
                f"The environment variable {variable_name!r} is not set"
                " and as such configuration could not be loaded. Set"
                " this variable and make it point to a configuration"
                " file"
            )
        return self.from_pyfile(rv, silent=silent)