Solution
app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite://' + os.path.join(basedir,'data.sqlite')
app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite+pysqlite:///' + os.path.join(basedir,'data.sqlite')
app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite://' + os.path.join(basedir,'data.sqlite')
app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite+pysqlite:///' + os.path.join(basedir,'data.sqlite')