flask-sqlalchemy常见异常错误Out of range value for column 'freeze_amount' 原因是字段超出范围【查看是否为负数，字段设置了无符号类型】_mysql 负数 out of range value for

如果mysql的字段设置了 无符号类型unsigned=True,一旦出现负数，就会如下错误提示

# 自定义无符号类型的Decimal
class OwnUnsignedDecimal(DECIMAL):
    # 指定unsigned为True代表无符号类型【不能是负数】,默认长度20为、小数点保留后6位
    def __init__(self, precision=20, scale=9, asdecimal=True, unsigned=True, **kw):
        super().__init__(precision=precision, scale=scale, asdecimal=asdecimal, unsigned=unsigned, **kw)

"description": "<p>全局异常错误捕捉：(pymysql.err.DataError) (1264, "Out of range value for column 'freeze_amount' at row 1")\n[SQL: UPDATE asset_trade_model SET eth_balance=%(eth_balance)s, freeze_token_amount=%(freeze_token_amount)s WHERE asset_trade_model.id = %(asset_trade_model_id)s]\n[parameters: {'eth_balance': Decimal('10.28200000000000000066613381'), 'freeze_token_amount': Decimal('-100.000000000'), 'asset_trade_model_id': 3}]\n(Background on this error at: http://sqlalche.me/e/9h9h)</p>",