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Below you will find an overview of this book, key sections from the Introduction, and information about the authors. Happy reading!
Renowned DAX experts Alberto Ferrari and Marco Russo teach you how to design data models for maximum efficiency and effectiveness
How can you use Excel and Power BI to gain real insights into your information? As you examine your data, how do you write a formula that provides the numbers you need? The answers to both of these questions lie with the data model. This book introduces the basic techniques for shaping data models in Excel and Power BI. It’s meant for readers who are new to data modeling as well as for experienced data modelers looking for tips from the experts. If you want to use Power BI or Excel to analyze data, the many real-world examples in this book will help you look at your reports in a different way—like experienced data modelers do. As you’ll soon see, with the right data model, the correct answer is always a simple one!
By reading this book, you will:
- Gain an understanding of the basics of data modeling, including tables, relationships, and keys
- Familiarize yourself with star schemas, snowflakes, and common modeling techniques
- Learn the importance of granularity
- Discover how to use multiple fact tables, like sales and purchases, in a complex data model
- Manage calendar-related calculations by using date tables
- Track historical attributes, like previous addresses of customers or manager assignments
- Use snapshots to compute quantity on hand
- Work with multiple currencies in the most efficient way
- Analyze events that have durations, including overlapping durations
- Learn what data model you need to answer your specific business questions
Excel users love numbers. Or maybe it’s that people who love numbers love Excel. Either way, if you are interested in gathering insights from any kind of dataset, it is extremely likely that you have spent a lot of your time playing with Excel, pivot tables, and formulas.
In 2015, Power BI was released. These days, it is fair to say that people who love numbers love both Power Pivot for Excel and Power BI. Both these tools share a lot of features, namely the VertiPaq database engine and the DAX language, inherited from SQL Server Analysis Services.
With previous versions of Excel, gathering insights from numbers was mainly a matter of loading some datasets and then starting to calculate columns and write formulas to design charts. Yes, there were some limitations: the size of the workbook mattered, and the Excel formula language was not the best option for huge number crunching. The new engine in Power BI and Power Pivot is a giant leap forward. Now you have the full power of a database and a gorgeous language (DAX) to leverage. But, hey, with greater power comes greater responsibility! If you want to really take advantage of this new tool, you need to learn more. Namely, you need to learn the basics of data modeling.
Data modeling is not rocket science. It is a basic skill that anybody interested in gathering insights from data should master. Moreover, if you like numbers, then you will love data modeling, too. So, not only is it an easy skill to acquire, it is also incredibly fun.
This book aims to teach you the basic concepts of data modeling through practical examples that you are likely to encounter in your daily life. We did not want to write a complex book on data modeling, explaining in detail the many complex decisions that you will need to make to build a complex solution. Instead, we focused on examples coming from our daily job as consultants. Whenever a customer asked us to help solve a problem, if we felt the issue is something common, we stored it in a bin. Then, we opened that bin and provided a solution to each of these examples, organizing them in a way that it also serves as a training on data modeling.
When you reach the end of the book, you will not be a data-modeling guru, but you will have acquired a greater sensibility on the topic. If, at that time, you look at your database, trying to figure out how to compute the value you need, and you start to think that—maybe—changing the model might help, then we will have accomplished our goal with this book. Moreover, you will be on your path to becoming a successful data modeler. This last step—that is, becoming a great data modeler—will only come with experience and after many failures. Unfortunately, experience is not something you can learn in a book.
Who this book is for
This book has a very wide target of different kind of people. You might be an Excel user who uses Power Pivot for Excel, or you may be a data scientist using Power BI. Or you could be starting your career as a business-intelligence professional and you want to read an introduction to the topics of data modeling. In all these scenarios, this is the book for you.
Note that we did not include in this list people who want to read a book about data modeling. In fact, we wrote the book thinking that our readers probably do not even know they need data modeling at all. Our goal is to make you understand that you need to learn data modeling and then give you some insights into the basics of this beautiful science. Thus, in a sentence if you are curious about what data modeling is and why it is a useful skill, then this is the book for you.
Assumptions about you
We expect our reader to have a basic knowledge of Excel Pivot Tables and/or to have used Power BI as a reporting and modelling tool. Some experience in analysis of numbers is also very welcome. In the book, we do not cover any aspect of the user interface of either Excel or Power BI. Instead, we focus only on data models, how to build them, and how to modify them, so that the code becomes easier to write. Thus, we cover “what you need to do” and we leave the “how to do it” entirely to you. We did not want to write a step-by-step book. We wanted to write a book that teaches complex topics in an easy way.
One topic that we intentionally do not cover in the book is the DAX language. It would have been impossible to treat data modeling and DAX in the same book. If you are already familiar with the language, then you will benefit from reading the many pieces of DAX spread throughout this book. If, on the other hand, you still need to learn DAX, then read The Definitive Guide to DAX, which is the most comprehensive guide to the DAX language and ties in well with the topics in this book.
About the authors
Alberto Ferrari and Marco Russo are the founders of sqlbi.com, where they regularly publish articles about Microsoft Power Pivot, Power BI, DAX, and SQL Server Analysis Services. Both Ferrari and Russo provide consultancy and mentoring on business intelligence (BI). They are also frequent speakers at major international conferences, including Microsoft Ignite, PASS Summit, and SQLBits.