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

Relational Databases and SQL

A relational database is a database that utilizes the relational model of data. The relational model, invented by Edgar F. Codd in 1970, organizes data as relations, or sets of tuples. Each tuple consists of a series of attributes, which generally describe the tuple. For example, we could imagine a customer relation, where each tuple represents a customer. Each tuple would then have attributes describing a single customer, giving information such as first name, last name, and age, perhaps in the format (John, Smith, 27). One or more of the attributes is used to uniquely identify a tuple in a relation and is called the relational key. The relational model then allows logical operations to be performed between relations.

In a relational database, relations are usually implemented as tables, as in an Excel spreadsheet. Each row of the table is a tuple, and the attributes are represented as columns of the table. While not technically required, most tables...