August 2022
Beginner to intermediate
463 pages
9h 22m
Chinese
Content preview from Tableau Prep即学即用
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282
第
32
章
实现高级连接
数据
Join
（连接）是用于准备所要分析数据的更强大的技术之一。将另一个数据集
添加到现有的数据中，可以为你提供更多关于为什么发生某些事情的上下文信息，
或者回答更多细化的问题。在第
16
章中，我们介绍了连接类型和连接条件的使用，
从而以一种简单的方式获得你想要的数据。然而，正如你在这一章中看到的那样，
有许多连接的用例，其中的逻辑是比较复杂的。
32.1
多连接条件
通常，连接两个数据集的过程需要的不仅仅是一个简单的、单一的连接条件。当使
用多个连接条件时，需要记住它们的行为是
AND
而不是
OR
语句。换句话说，要
想让被评估的数据记录被连接步骤的内部处理机制输出，必须满足每个连接条件。
在挑战赛示例中，
Preppin
’
Data 2020
：第
8
周挑战赛（
https://oreil.ly/m_WoZ
），将
Actual Volume
（商品销量）和
Value
（销售额）数据集（见图
32-1
）加入
Profit
（利
润）数据集（见图
32-2
）需要多个连接条件。
｜
283
实现高级连接
图
32
-
1
：Actual Volume（商品销量）和 Value（销售额）数据集
图
32
-
2
：Profit（利润）数据集
每个数据集只有
16
行数据，但只有一个连接条件（
Type
），连接的输出是
128
行（ 见
图
32-3 ...
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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.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
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.