报错信息

/opt/virtualenv/flask/lib/python3.6/site-packages/flask_sqlalchemy/__init__.py:839: FSADeprecationWarning: SQLALCHEMY_TRACK_MODIFICATIONS adds significant overhead and will be disabled by default in the future.  Set it to True or False to suppress this warning.
'SQLALCHEMY_TRACK_MODIFICATIONS adds significant overhead and '

仔细看这个翻译

 SQLALCHEMY_TRACK_MODIFICATIONS  这个属性以后默认会是Disable的，如果需要用的话，自己手动设置成True 或False

解决办法

 直接根据自己的实际情况，设置SQLALCHEMY_TRACK_MODIFICATIONS的值为True或False即可

官方配置说明文档

 http://flask-sqlalchemy.pocoo.org/2.1/config/

If set to True, Flask-SQLAlchemy will track modifications of objects and emit signals. The default is None, which enables tracking but issues a warning that it will be disabled by default in the future. This requires extra memory and should be disabled if not needed.