Lots of SQL code illustrate a simple but not exotic example of a software application: a data transfer between two computer systems. An SQL exercise, a practical example to show the simplicity and power of this so popular language, which, used correctly, can still work wonders. A non-fiction book with elements of fiction is one of the paradoxes of this book written by an SQL programmer who loves to write and does not necessarily have an extremely technical style. This combination of elements makes the book enjoyable, not only useful. Here you can find a book full of SQL scripts, using perhaps the most popular database systems: SQL Server and Oracle. As Stefan calls it, this SQL exercise can be helpful in many categories of people, programmers of all kinds who use the SQL language, students at computer science universities, analysts or testers in IT companies, etc. Because, despite its age, the SQL language is still very current. And another big paradox is that the quality of SQL code is often poor enough to create severe problems in many computer systems. In a way, this book is a continuation of the previous one, Relational Database Programming: A Set-Oriented Approach, where the author tries to promote the set-based style of development in the relational database. This style is considered the default here, and this SQL exercise illustrates this programming paradigm. Today, the SQL language is somehow hidden in the shadows, like the balrog of the "Lord of the Rings." A programmer like Gandalf could use his walking stick and bring to the light what is best in this language. That's what Stefan is trying to do in this book. Nowadays, a lot of SQL code is written and maintained by application developers like Java or C#. Sometimes this is not an issue, but quite often, it is. However, certain types of systems only manipulate data in a relational format, and it would be a bad idea not to use anything else than SQL. Speedy is a kind of such system.Now, in the age of the cloud, artificial intelligence, and the attack of new technologies, is SQL still relevant? Despite more than half a century of existence, the SQL language is still present almost everywhere. Almost everyone uses this language. This broad applicability seems to be the cause of many performance issues, as the simplicity of the language is only apparent. It is effortless for any programmer to write sub-optimal SQL code, which causes excessive execution times and even blockages of all kinds.This SQL exercise will be an active-passive one. If one wants, the reader can practice because Stefan challenges the user to continue his work on one side or another. This SQL exercise is an open one, and the reader has the freedom and is encouraged to continue Stefan's work. There is some homework inside the book, and the author hopes that some readers will effectively use what's here in their projects. Apart from the main book goal, the SQL knowledge, the author gives a specific note to his work, partially narrative and fictional. The series of fictional characters who live in the book "Speedy" provide a splash of color to a technical book and, on the other hand, once again confirms the pragmatic note of the SQL language, such a natural and intuitive language. Just see the main keywords of SQL and see such common words as select, insert or delete. Master Johnny and Jean-Luc, Angelique, and Joanna are not just simple characters of a software company. These characters are reflections of the language, after all.
