SQL is the ubiquitous language for software developers working with structured data. Most developers who rely on SQL are experts in their favorite language (such as Java, Python, or Go), but they're not experts in SQL. They often depend on antipatterns - solutions that look right but become increasingly painful to work with as you uncover their hidden costs. Learn to identify and avoid many of these common blunders. Refactor an inherited nightmare into a data model that really works. Updated for the current versions of MySQL and Python, this new edition adds a dozen brand new mini-antipatterns for quick wins.

No matter which platform, framework, or language you use, the database is the foundation of your application, and the SQL database language is the standard for working with it. Antipatterns are solutions that look simple at the surface, but soon mire you down with needless work. Learn to identify these traps, and craft better solutions for the often-asked questions in this book. Avoid the mistakes that lead to poor performance and quality, and master the principles that make SQL a powerful and flexible tool for handling data and logic.

Dive deep into SQL and database design, and learn to recognize the most common missteps made by software developers in database modeling, SQL query logic, and code design of data-driven applications. See practical examples of misconceptions about SQL that can lure software projects astray. Find the greatest value in each group of data. Understand why an intersection table may be your new best friend. Store passwords securely and don't reinvent the wheel. Handle NULL values like a pro. Defend your web applications against the security weakness of SQL injection.

Use SQL the right way - it can save you from headaches and needless work, and let your application really shine!

What You Need:

The SQL examples use the MySQL 8.0 flavor, but other popular brands of RDBMS are mentioned. Other code examples use Python 3.9+ or Ruby 2.7+.

Table of Contents

1.What's an Antipattern?

Part I Logical Database Design Antipatterns

2. Jaywalking

3. Naive Trees

4. ID Required

5. Keyless Entry

6. Entity-Attribute-Value

7. Polymorphic Associations

8. Multicolumn Attributes

9. Metadata Tribbles

Part II Physical Database Design Antipatterns

10. Rounding Errors

11. 31 Flavors

12. Phantom Files

13. Index Shotgun

Part III Query Antipatterns

14. Fear of the Unknown

15. Ambiguous Groups

16. Random Selection

17. Poor Man's Search Engine

18. Spaghetti Query

19. Implicit Columns

Part IV Application Development Antipatterns

20. Readable Passwords

21. SQL Injection

22. Pseudokey Neat-Freak

23. See No Evil

24. Diplomatic Immunity

25. Standard Operating Procedures

Part V Bonus: More Foreign Key Mini-Antipatterns

26. Foreign Key Mistakes in Standard SQL

27. Foreign Key Mistakes in MySQL

A1 . Rules of Normalization

About the Author

Bill Karwin has been a software engineer for over thirty years, developing and supporting applications, libraries, and servers, and consulting for leading technology companies. Throughout his career, Bill has shared his knowledge to help other programmers achieve success and productivity. Bill has answered thousands of questions, giving him a unique perspective on SQL mistakes that most commonly cause problems.