【摘要】 针对现有多级关系数据模型中存在的数据重复率大、复杂安全格的置信不明确、主键漏洞等问题,该文定义了一种新的多级安全关系数据模型—CMLR。该数据模型继承多个现有数据模型的优点,重定义了完整性规则和操作语义,通过采用基表和衍生表、实体标识符、显式和隐式置信等手段,将数据重复率由元组级降至元素级,明确了复杂安全格的置信规则,消除了主键漏洞。CMLR模型能够有效地提供元素级的强制访问控制。更多还原

【Abstract】 Regarding the problem of high rate of data repeating,inexplicitness of complex lattice believing and the key loophole in existing multilevel relational data model,this paper defines a new model-CMLR.Carrying on the advantages of several existing data models,CMLR redefines integrity rule and operation semantics,CMLR reduces the rate of data repeating from tuple level to element level,clarifies the believing regulation of the complex lattice and eliminates the key loophole.CMLR provides element level mandatory access control.更多还原