This week should have been very productive. Week 3 shows you the flexibility of SQL, explains how you can apply these features to real-world problems, and introduces some popular extensions to SQL. You should know how to use the tools that are available with your implementation of SQL to make your code more readable. By now you realize that all implementations of SQL share the same general concepts, although the syntax may differ slightly.

You should have a clear understanding of the data dictionary, what data it contains, and how to retrieve useful information from it. If you understand how to generate SQL from another SQL statement, you should be ready to fly to unlimited heights.

What about errors? You will never be immune from syntax errors or logical mistakes, but as you gain experience with SQL, you will learn how to avoid many problems. But then again, errors can be excellent learning opportunities.

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