chapter two

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, you may start by reading chapter 1.

If you want to try the SQL queries covered in this chapter, you need to load a prepared SQL script into a RDBMS to generate a few tables with data. You can find the target scripts in the chapter_02 folder in our GitHub repository (https://github.com/Neo-Hao/grokking-relational-database-design), and follow the instructions in the README.md file to load the script. For example, the easiest approach is to use SQLite Online:

  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).
  4. Click Import to load the script named sqlite_online.sql.
  5. Click Okay.

2.1 Overview

In Chapters 1, you learned the basics of SQL and how to query or create a single table. In this chapter, you will continue learning a bit more of SQL by querying and creating related tables. In the end, you will peek into how to pick up more SQL keywords by yourself in the future.

2.2 Related tables

2.2.1 Number(s) of shared columns

2.2.2 Join data from related tables

2.3 Revisit table and data management

2.3.1 Manage related tables

2.3.2 Manage data in related tables

2.4 Learn more SQL on your own

2.5 Summary