def robotsrulesetOfDomain(self, domain):
		'''检查domain是否在数据库中,
			否 --> (False, None)
			是 --> (True, 数据库中存储的robots.txt内容)
		'''
		exist = False
		cur = self.conn.cursor()
		# 是否存在
		cur.execute("SELECT 1 FROM Domains WHERE domain=?", (domain,))
		if cur.fetchone() :
			exist = True
		# 存在的话,结果是什么
		cur.execute("SELECT rules FROM Domains,Rulesets "
			"WHERE domain=? AND Domains.did=Rulesets.did"
			,(domain,) )
		ruleset = cur.fetchone()
		return (exist, ruleset)
def export(self, location, url):
        # type: (str, HiddenText) -> None
        """Export the Git repository at the url to the destination location"""
        if not location.endswith('/'):
            location = location + '/'

        with TempDirectory(kind="export") as temp_dir:
            self.unpack(temp_dir.path, url=url)
            self.run_command(
                ['checkout-index', '-a', '-f', '--prefix', location],
                show_stdout=False, cwd=temp_dir.path
            )