If you have gotten to this chapter and covered all the material to this point, congrats! You have learned an adaptable and marketable skillset that can be applied to the fields of business, information technology, and engineering. With consistent practice and usage, you should feel comfortable positioning yourself professionally with SQL and database design.
When it comes to understanding and using technology, everyone has a different level of ambition. You may very well have read this book and see this material as not central to your career goals, but rather complementary. This may be the case if you are an interdepartmental manager of sorts and just want to understand IT a little better. You may feel this book has given all the insight you need, which is perfectly acceptable. Only you can define your career goals and prioritize what maximizes your value!
But perhaps SQL has really clicked with you, and you have questions on how you can do more. Maybe you want to have a deeper knowledge of SQL and business intelligence. Or maybe you want to create software and graphical user interfaces that interact with a database. After reading this material, you may feel you are not done and have unanswered questions on how to create full business solutions. If this is you, I encourage you to keep researching and pursuing whatever knowledge you need to fulfill your goals.
If you want to learn more detailed functionalities in SQL, there are plenty of books and resources ...