sqlalchemy.exc.InternalError: (pymysql.err.InternalError) (1832, u"Cannot change column 'lb_algorithm': used in a foreign key constraint 'fk_pool_algorithm_name'") [SQL: u'ALTER TABLE pool MODIFY lb_algorithm VARCHAR(255) NOT NULL']
sqlalchemy. exc.InternalErr or: (pymysql. err.InternalErr or) (1832, u"Cannot change column 'lb_algorithm': used in a foreign key constraint 'fk_pool_ algorithm_ name'") [SQL: u'ALTER TABLE pool MODIFY lb_algorithm VARCHAR(255) NOT NULL']