July 2025
Beginner to intermediate
386 pages
5h 25m
Chinese
Content preview from 学习 SPARQL，第 2 版
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第 1 章.直接进入：一些数据和一些查询
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第 2 章提供了一些关于 RDF、语义网和 SPARQL 的背景知识，但在介绍这些知识之前，让我们先从编写和运行 SPARQL 查询的实践经验开始，以免背景知识部分显得过于理论化。
首先，什么是 SPARQL ？这个名字是 SPARQL 协议和 RDF 查询语言的递归首字母缩写，由 W3C 的一套规范描述。
注释
W3C ，即万维网联盟，是负责 HTML、XML 和 CSS 的同一标准机构。
从其名称中的 "RQL "部分可以看出，SPARQL 是为查询 RDF 而设计的，但您并不局限于查询以 RDF 格式之一存储的数据。商业和开源实用程序可将关系数据、XML、JSON、电子表格和其他格式的数据视为 RDF，因此您可以针对这些格式的数据或这些数据源的组合发出 SPARQL 查询，这是 SPARQL/RDF 组合最强大的方面之一。
SPARQL 名称中的 "协议"部分指的是客户端程序和 SPARQL 处理服务器之间交换 SPARQL 查询和结果的规则。这些规则在查询规范文档之外的另一份文档中规定，主要是 SPARQL 处理器开发人员的问题。使用查询语言可以走得很远，无需担心协议问题，因此本书不对其进行详细介绍。
要查询的数据
第 2 章将介绍更多有关 RDF 的内容以及人们使用 RDF 所做的各种事情，但我们可以总结一下：RDF 不是一种数据格式，而是一种数据模型，有多种语法可供选择，用于存储数据文件。在这种数据模型中，你可以用三部分语句来表达事实，这些语句被称为三元组 。每个三元组就像一个陈述事实的小句子。我们将三元组的三个部分分别称为主语 、谓语 和宾语 ，但您也可以将它们视为被描述事物（"资源"；RDF 是 "资源描述框架"的缩写）的标识符、属性 名称和属性值：
| 主题（资源标识符） | 谓词（属性名称） | 对象（属性值） |
| 理查德 | 家庭电话 | (229) 276-5135 |
| 辛迪 | 电子邮件 | cindym@gmail.com |
下面的 ex002.ttl 文件使用Turtle RDF 格式表达了一些三元组。(我们将在第 2 章中学习 Turtle 和其他格式。）该文件使用三元组存储地址簿数据，这些三元组的语句包括 "richard 的 homeTel 值是 (229) 276-5135 "和 "cindy 的 email 值是 cindym@gmail.com"。RDF 对给定资源的给定属性分配多个值没有问题，正如您在此文件中看到的，该文件显示 Craig 有两个电子邮件地址：
# filename: ex002.ttl @prefix ab: <http://learningsparql.com/ns/addressbook#> . ab:richard ab:homeTel "(229) 276-5135" . ab:richard ab:email "richard49@hotmail.com" . ab:cindy ab:homeTel "(245) 646-5488" . ab:cindy ab:email "cindym@gmail.com" . ab:craig ab:homeTel "(194) 966-1505" . ab:craig ab:email "craigellis@yahoo.com" . ab:craig ab:email "c.ellis@usairwaysgroup.com" .
与英文句子一样，Turtle（和 ...
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