添加在导入包后的位置
#models.py #from ..... if __name__ == ‘__main__‘: db.metadata.clear()
InvalidRequestError: Table is already defined for this MetaData instance. Specify 'extend_existing=True' to redefine options and columns on an existing Table object.
原文：https://www.cnblogs.com/edhg/p/8907300.html
