【摘要】 本文在［１］扩展关系模型中引入属性级的不完全信息空值。为适应此环境下更新操作的需要，本文对［１］中的扩展关系模型进行了进一步的扩展，并以此模型为基础讨论了空值环境下含不确定及可能信息关系数据库的更新操作的策略，给出了相应的处理算法。更多还原

【Abstract】 Null value is introduced to the extended relational model of paper [1]. To update the relational database under such circumstance, the extended relational model in paper [1] is further extended. On the basis of the extended model, the policy of updating relational database containing indefinite and maybe informations under null value circumstances is discussed, and the relevant algorithm of processing is given.更多还原