2 Related tables and more SQL

 

In this chapter

  • You learn what related tables are and how to query them.
  • You revisit table and data management.
  • You explore how to learn more SQL on your own.
What you need to know

To understand the SQL covered in this chapter, you need to know what databases and tables are, as well as the basics of SQL queries. If not, read chapter 1 first.

As you read this chapter, you will find more code snippets. If you want to execute those code snippets or see their variations for different relational database management systems (RDMBSs), check the GitHub repository that accompanies this book (https://github.com/Neo-Hao/grokking-relational-database-design). You can find the scripts for this chapter in the chapter_02 folder; follow the instructions in the README.md file to run the scripts.

The easiest approach is to use SQLite Online as follows:

  1. Clone or download our GitHub repository (https://github.com/Neo-Hao/grokking-relational-database-design).
  2. Locate the scripts in the chapter_02 folder.
  3. Visit SQLite Online (https://sqliteonline.com). Choose your target RDBMS in the left sidebar and click Click to Connect.
  4. Click Import to load the script corresponding to your chosen RDBMS (such as mysql_db.sql from the downloaded or cloned GitHub repository for MariaDB).
  5. Click Okay.

Overview

Related tables

Number(s) of shared columns

Join data from related tables

Types of JOINS

WHERE vs. JOIN

Revisit table and data management

Manage related tables

Manage data in related tables

Learn more SQL on your own