August 2022
Beginner to intermediate
463 pages
9h 22m
Chinese
Content preview from Tableau Prep即学即用
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404
第
46
章
在数据中使用标识符和键
正如在前面的多个章节中提到的那样，数据库被设计为功能强大、性能优异、安全
存储和处理数据的场所。在组织中使用的大多数数据库的核心包含两个概念，即
Key
（键）和
Identifier
（
ID
，标识符
ID
）。运用这些概念的数据库被称为关系型数
据库，因为键和
ID
字段在各种数据表之间建立了关系。在本章中，我们将研究
ID
字段，它们如何用作表之间的键，以及如何在
Prep Builder
中创建它们。
46.1
什么是标识符
与大多数计算软件一样，数据库中的数字比其他字符的处理效率更高。在进行数据
处理时，经常需要处理大量的数据，因此可以使用任何方法来提高处理效率，这可
以对数据准备或进行分析所需的时间产生重大影响，这就是数据库的
ID
字段发挥作
用的地方。关系型数据库架构师不会重复存储姓名、地址或其他长字符串值，而会
使用单独的
Look-up Tables
（查找表）来存储这些值，只需存储一次，并将一个标
识符与该值关联起来。如图
46-1
所示的采购表有许多
ID
字段，我们可以用这些
ID
字段将其他带有客户或产品名称的
Reference Tables
（参考表）连接在一起。包含交
易清单或类似指标的表通常被称为
Fact Tables
（事实表）。
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I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
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I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.