Book Image

SQL for Data Analytics - Third Edition

By : Jun Shan, Matt Goldwasser, Upom Malik, Benjamin Johnston
Book Image

SQL for Data Analytics - Third Edition

By: Jun Shan, Matt Goldwasser, Upom Malik, Benjamin Johnston

Overview of this book

Every day, businesses operate around the clock, and a huge amount of data is generated at a rapid pace. This book helps you analyze this data and identify key patterns and behaviors that can help you and your business understand your customers at a deep, fundamental level. SQL for Data Analytics, Third Edition is a great way to get started with data analysis, showing how to effectively sort and process information from raw data, even without any prior experience. You will begin by learning how to form hypotheses and generate descriptive statistics that can provide key insights into your existing data. As you progress, you will learn how to write SQL queries to aggregate, calculate, and combine SQL data from sources outside of your current dataset. You will also discover how to work with advanced data types, like JSON. By exploring advanced techniques, such as geospatial analysis and text analysis, you will be able to understand your business at a deeper level. Finally, the book lets you in on the secret to getting information faster and more effectively by using advanced techniques like profiling and automation. By the end of this book, you will be proficient in the efficient application of SQL techniques in everyday business scenarios and looking at data with the critical eye of analytics professional.
Table of Contents (11 chapters)
9
9. Using SQL to Uncover the Truth: A Case Study

3. SQL for Data Preparation

Activity 3.01: Building a Sales Model Using SQL Techniques

Solution:

  1. Open pgAdmin, connect to the sqlda database, and open the SQL query editor.
  2. Use INNER JOIN to join the customers table to the sales table:
    FROM sales s
    JOIN customers c
    ON s.customer_id = c.customer_id

Note that the SQL in Steps 2, 3, and 4 is not complete SQL that you can run in pgAdmin. They are part of the FROM…JOIN clause on which the full SELECT statement will be built. They are created to guide you through the process of forming a complex dataset using JOIN. If you want to test the SQL, you can make it complete by adding SELECT * at the start.

  1. Use INNER JOIN to join the products table to the sales table:
    FROM sales s
    JOIN customers c
    ON s.customer_id = c.customer_id
    JOIN products p
      ON s.product_id = p.product_id
  2. Use LEFT JOIN to join the dealerships table (right table) to the sales table (left table):
    FROM sales s
    LEFT JOIN dealerships...