Book Image

SQL for Data Analytics

By : Upom Malik, Matt Goldwasser, Benjamin Johnston
3 (1)
Book Image

SQL for Data Analytics

3 (1)
By: Upom Malik, Matt Goldwasser, Benjamin Johnston

Overview of this book

Understanding and finding patterns in data has become one of the most important ways to improve business decisions. If you know the basics of SQL, but don't know how to use it to gain the most effective business insights from data, this book is for you. SQL for Data Analytics helps you build the skills to move beyond basic SQL and instead learn to spot patterns and explain the logic hidden in data. You'll discover how to explore and understand data by identifying trends and unlocking deeper insights. You'll also gain experience working with different types of data in SQL, including time-series, geospatial, and text data. Finally, you'll learn how to increase your productivity with the help of profiling and automation. By the end of this book, you'll be able to use SQL in everyday business scenarios efficiently and look at data with the critical eye of an analytics professional. Please note: if you are having difficulty loading the sample datasets, there are new instructions uploaded to the GitHub repository. The link to the GitHub repository can be found in the book's preface.
Table of Contents (11 chapters)
9
9. Using SQL to Uncover the Truth – a Case Study

Performant Joins

The JOIN functionality in SQL-compliant databases provides a very powerful and efficient method of combining data from different sources, without the need for complicated looping structures or a series of individual SQL statements. We covered joins and join theory in detail in Chapter 3, SQL for Data Preparation. As suggested by the name of the command, a join takes information from two or more tables and uses the contents of the records within each table to combine the two sets of information. Because we are combining this information without the use of looping structures, this can be done very efficiently. In this section, we will consider the use of joins as a more performant alternative to looping structures. The following is the Customer Information table:

Figure 8.33: Customer information

The following table shows the Order Information table:

Figure 8.34: Order information

So, with this information, we may want...