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 _db_schema_sanity_check(engine):
    """Ensure all database tables were created with required parameters.

    :param engine:  SQLAlchemy engine instance for a given database

    """

    if engine.name == 'mysql':
        onlyutf8_sql = ('SELECT TABLE_NAME,TABLE_COLLATION '
                        'from information_schema.TABLES '
                        'where TABLE_SCHEMA=%s and '
                        'TABLE_COLLATION NOT LIKE "%%utf8%%"')

        table_names = [res[0] for res in engine.execute(onlyutf8_sql,
                                                        engine.url.database)]
        if len(table_names) > 0:
            raise ValueError(_('Tables "%s" have non utf8 collation, '
                               'please make sure all tables are CHARSET=utf8'
                               ) % ','.join(table_names))