Book Image

The MySQL Workshop

By : Thomas Pettit, Scott Cosentino
5 (1)
Book Image

The MySQL Workshop

5 (1)
By: Thomas Pettit, Scott Cosentino

Overview of this book

Do you want to learn how to create and maintain databases effectively? Are you looking for simple answers to basic MySQL questions as well as straightforward examples that you can use at work? If so, this workshop is the right choice for you. Designed to build your confidence through hands-on practice, this book uses a simple approach that focuses on the practical, so you can get straight down to business without having to wade through pages and pages of dull, dry theory. As you work through bite-sized exercises and activities, you'll learn how to use different MySQL tools to create a database and manage the data within it. You'll see how to transfer data between a MySQL database and other sources, and use real-world datasets to gain valuable experience of manipulating and gaining insights from data. As you progress, you'll discover how to protect your database by managing user permissions and performing logical backups and restores. If you've already tried to teach yourself SQL, but haven't been able to make the leap from understanding simple queries to working on live projects with a real database management system, The MySQL Workshop will get you on the right track. By the end of this MySQL book, you'll have the knowledge, skills, and confidence to advance your career and tackle your own ambitious projects with MySQL.
Table of Contents (22 chapters)
1
Section 1: Creating Your Database
6
Section 2: Managing Your Database
11
Section 3: Querying Your Database
16
Section 4: Protecting Your Database

Introduction to processing data across tables

In the previous chapter, we covered querying a single table. We used WHERE to filter out the rows we were interested in, and we used GROUP BY to aggregate rows into groups of rows to then use aggregate functions such as COUNT() and SUM(). We also learned about working with JSON data.

In a relational database such as MySQL, data is stored across multiple tables. The reason for doing this is that it avoids storing the same piece of information multiple times.

An example of this is a database for a simple website with comments. It probably has a table of users consisting of values such as username, display name, and password hash. Then it has a table named posts that stores all the posts, and then there is a table with comments. The comment table stores a reference to the post the comment is linked to and a reference to the user commenting.

If the user changes their password, then only one table has to be updated. And if a comment...