报错：peewee.OperationalError: Connection already opened，用过的解决方案：1. 将数据库插入语句放在视图函数里；2. 使用模板改为使用接口；

相关资料	网址
Connection Management	http://docs.peewee-orm.com/en/latest/peewee/database.html?highlight=Connection already opened#connection-management
Connection Already Open	https://teamtreehouse.com/community/connection-already-open
Framework Integration: Flask	http://docs.peewee-orm.com/en/latest/peewee/database.html#flask
«Connection already open» when trying to get data from session_interface in flask	https://github.com/coleifer/peewee/issues/1557