Are similar to hierarchical ones , but they allow multiple parent child relations 与层次数据库类似,但它们允许多个父子关系。
In a hierarchical database hdbms , you begin with a strictly defined tree of data nodes 在层次数据库( hdbms )中,首先是从严格定义的数据节点树开始的。
Research on the algorithm for mining generalized association rules based on taxonomic quantitative databases 一种基于概念层次数据库挖掘一般化关联规则的算法研究
But in dtds oriented more to data records , an xml document could be as rigid as a hierarchical database 但dtd更多地是面向数据记录, xml文档和层次数据库可以一样严格。
This goal is accomplished almost automatically in hierarchical databases , but takes work in relational ones 这个目标在层次数据库中几乎是自动完成的,但在关系数据库中需要做些工作。
Figure 2 illustrates relational database structure covering roughly the same data as the hierarchical example 图2说明了关系数据库的结构(使用几乎和层次数据库示例中相同的数据) 。
Generally speaking , h ierarchical databases arose in the 1960s , on the mainframe data processing technology of the time 一般而言,层次数据库兴起于60年代,用在当时的大型机数据处理技术方面。
In hierarchical databases , data access is utterly predictable in structure ; therefore both retrieval and updates can be highly optimized by a dbms 在层次数据库中,数据访问在结构上是完全可预测的;因此dbms可以高度优化检索和更新。
The database theory starts for 1960s , and come through hierarchical model database system , network model database system , and relational model database system 数据库技术始于20世纪60年代,几十年来,数据库技术的发展经历了由层次数据库系统、网状数据库系统,到关系数据库系统。
The second part is the main part of the paper . it put forwards several new thoughts as communication middleware , servant middleware , and entity object etc . , and designs several new multi - tiered database models 第二部分首先对论文涉及到相关知识进行了比较和分析;然后,通过中间件和实体对象的构造等方法进行分布式多层次数据库模型的设计。