Introduction

Throughout SQL for Data Analytics, you have learned a range of new skills, including basic descriptive statistics, SQL commands and importing and exporting data in PostgreSQL, as well as more advanced methods, such as functions and triggers. In this final chapter of the book, we will combine these new skills with the scientific method and critical thinking to solve the real-world problem of understanding the cause of an unexpected drop in sales. This chapter provides a case study and will help you to develop confidence in applying your new SQL skillset to your own problem domains. To solve the problem presented in this use case, we will use the complete range of your newly developed skills, from using basic SQL searches to filter out the available information to aggregating and joining multiple sets of information and using windowing methods to group the data in a logical manner. By completing case studies such as this, you will refine one of the key tools in your data...