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Rating: 
Summary: overwhelmed by any SQL syntax? Then read this book!
Review:
This is a pretty good book. It's strength lies in it's limited scope: you learn relational database query languages, and get a short primer on Access (Microsoft) and WinRDBI (by author). It doesn't give you the various SQL dialects that exist (Oracle, MySQL, etc.), because that would make it a whole lot thicker book.
If you are overwhelmed by the vast syntax of any particular SQL flavor, than this is the book for you. Here is tersely presented what a minimal language needs, and why it is convenient to have a bigger language (ie. larger syntax).
The book teaches 4 relational "languages", each with it's own chapter: relational algebra, domain relational calculus (DRC), tuple relational calculus (TRC), and SQL. The preface states that relational algebra is considered crucial to understanding SQL. DRC is treated because it is often used for data mining techniques and artificial intelligence applications. TRC is treated because it's very similar to SQL. And SQL is the very reason that I picked up this book.
Each of these four chapters first introduces the basics of the language at hand.And then the language is further explained with example queries. For these examples a data model for an "employee training enterprise" is used; this data model was introduced in chapter 1. Chapter 1 also introduces entity relationship diagrams that are used to explain the data model.
Having the same data model and queries reappear in these different languages, makes that the reader picks up each language easily.
From the chapter on relational algebra you learn what the minimum set of operators is, that you need to express most queries that you might think of. And that it is convenient to have more operators, for common combinations of the basic operators.
In the following chapters on DRC, TRC, and SQL, this is the leading theme. In addition you learn of alternative queries to obtain a particular result, and how to choose between these alternatives.
In chapter 6 three case studies are presented, in all 4 languages. Chapter 7 is on Access, and appendix A on WinRDBI. WinRDBI can handle queries in all 4 presented languages.
The chapter on SQL is longer than the others. It explains such items as:
Safety : making sure that your query produces a finite result.
Query optimization : writing queries that execute quickly.
Sorting, grouping.
Defining tables.
What is given (almost) no mention is why/how to add indices to attributes.
Rating: 
Summary: Uncovers the mystery of SQL's behavior
Review: I like this book. I was looking for a book that gave the "why" behind SQL. I graduated years ago with a Computer Science degree and didn't have the opportunity to take a database class. I found myself having to learn SQL on the job. This book uncovers the mystery of SQL's behavior. It has a lot of examples that are supported by the software described in the appendix. It also describes how to use the query languages of Microsoft Access.Don't let the term "theory" scare you. After the first couple of pages of required definitions, the tone of the book quickly changed to a very readable presentation. Overall, I like the writing style - it's precise and to the point - not too wordy. Definitely worth the money!
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