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. Using SQL to Uncover the Truth – a Case Study

Using Array Data Types in Postgres

While the Postgres data types that we have explored so far allow us to store many different types of data, occasionally we will want to store a series of values in a table. For example, we might want to store a list of the products that a customer has purchased, or we might want to store a list of the employee ID numbers associated with a specific dealership. For this scenario, Postgres offers the ARRAY data type, which allows us to store just that – a list of values.

Starting with Arrays

Postgres arrays allow us to store multiple values in a field in a table. For example, consider the following first record in the customers table:

customer_id        | 1
title              | NULL
first_name          | Arlena
last_name          ...