2. 计算机
  3. One of the difficulties in building an SQL-like query lange for the Web is the absence of a database schema for this huge, heter

One of the difficulties in building an SQL-like query lange for the Web is the absence of a database schema for this huge, heter

admin2009-02-15  50
问题 One of the difficulties in building an SQL-like query lange for the Web is the absence of a database schema for this huge, heterogeneous repository of information. However, if we are interested in HTML documents only, we can construct a virtual(66)from the implicit structure of these files. Thus, at the highest level of(67), every such document is identified by its Uniform Resource Locator(URL), has a title and a text Also, Web servers provide some additional information such as the type, length, and the last modification date of a document. So, for data mining purposes, we can consider the site of all HTML documents as arelation:
   Document(url,(68), text, type, length, modify)
   Where all the(69)are character strings. In this framework, anindividual document is identified with a(70)in this relation. Of course, if some optional information is missing from the HTML document, the associate fields will de left blank, but this is not uncommon in any database.
选项 A、event
B、title
C、driver
D、table
答案B
解析
转载请注明原文地址:https://kaotiyun.com/show/JIJZ777K
本试题收录于： 网络工程师上午基础知识考试题库软考中级分类
0

网络工程师上午基础知识考试

软考中级

相关试题推荐
随机试题
最新回复(0)