Customer Reviews

XQuery

5 star:		(7)
4 star:		(1)
3 star:		(2)
2 star:		(0)
1 star:		(0)

 

 

I've had this XQuery book for about a week now and it has already helped me immensely! Priscilla Walmsley (who was a member of the W3C XML Schema Working Group and I believe the XQuery Working Group as well) is an excellent writer and teacher. Her writing style is clear and concise, as anyone who read her earlier Definitive XML Schema book already knows.

"XQuery" is roughly 2/3 tutorial and 1/3 reference (by page counts). The tutorial material is thoughtfully divided into 25 bite-size chapters. The topics progress nicely from an overview and basics to important concepts such as namespace handlng, modules and static typing. The book includes 5 chapters that focus on handling specific data types (e.g, "Working with Strings"). You don't have to know XSLT but knowing XPath may be helpful. OTOH, XPath is covered in Chap. 4. There is even a chapter targeted at SQL users. I also appreciate the carefully chosen running example that is representative of many XML structures. The book also benefits from special icons indicating tips, gotchas, and compatibility issues. Longtime XML geek Simon St.Laurent was the O'Reilly editor, which is another big plus.

Walmsley has also created an incredibly useful reference site of XQuery functions, both those defined by the W3C specs and numerous others that she wrote. Others may contribute as well. [...]

I have several older XQuery books by various publishers but this book is by far the best. I highly recommend it to web developers, database developers, and data architects with even a modest XML background.

The use of XML has become ubiquitous over the last five years, and thus a huge amount of data is now stored in XML, both as databases and as documents. XML data can include highly structured data such as sales figures, less structured data such as product catalogs, and unstructured data such as books. With such a variety of data stored as XML, in each case different elements of the data must be formatted and transformed in a particular way. This is where XQuery comes in. It is a query language that allows the user to select those XML data elements of interest, reorganize them, transform them, and finally return the results in a data structure. This book acts as an up-to-date tutorial and reference on this useful technology. There are plenty of examples shown that illustrate the concepts being presented. The following is a detailed description of the book's contents:

1. Introduction to XQuery - Provides the basic purpose and capabilities of XQuery and also acts as a quick introduction to its features. It provides a basic familiarity with the most commonly used kinds of expressions, without getting too bogged down in the details.

2. XQuery Foundations - a brief overview of the foundations of XQuery including its design, its place among XML-related standards, and its processing model. It also discusses the underlying data model behind XQuery and the use of types and namespaces in queries.

3. Expressions: XQuery Building Blocks - The basic unit of evaluation in XQuery is the expression. A query contains expressions that can be made up of a number of sub-expressions, which may themselves be composed from other sub-expressions. This chapter explains the XQuery syntax, and covers the most basic types of expressions that can be used in queries: literals, variables, function calls, and comments.

4. Navigating Input Documents Using Paths - Path expressions navigate input documents to select elements and attributes of interest. This chapter explains how to use these path expressions to select elements and attributes from an input document and apply predicates to filter those results. It also covers the different methods of accessing input documents.

5. Adding Elements and Attributes to Results - Queries often include some XML elements and attributes that structure the results. This chapter explains how you can create entirely new elements and attributes and include them in your results.

6. Selecting and Joining Using FLWORs - Describes the facilities in XQuery for selecting, filtering, and joining data from one or more input documents. Included is the syntax of FLWORs (for, let, where, order by, return) and quantitative expressions.

7. Sorting and Grouping - How to sort and group data from input documents. This chapter covers sorting in FLWORs, grouping results together, and calculating summary values using the aggregation functions.

8. Functions - Describes this useful feature of XQuery that allow a wide array of built-in functionality, as well as the ability to modularize and reuse parts of queries. There are two kinds of functions: built-in functions and user-defined functions, and this chapter looks at them both.

9. Advanced Queries - Describes syntax and techniques for some commonly requested query capabilities by showing you some creative ways to apply XQuery syntax.

10. Namespaces and XQuery - The first part provides a refresher on namespaces in XML input documents in general. Next the use of namespaces in queries is covered including how to declare and refer to them and how to control their appearance in your results.

11. A Closer Look at Types - Goes into detail on the set of built-in types in XQuery. A good explanation of the automatic type conversions performed by the processors and a description of the expressions that are relevant to type constructors, cast and castable expressions, and instance of expressions.

12. Queries, Prologs, and Modules - Discusses the structure of queries starting with the query prolog and its various declarations. The assembly of queries from multiple modules, declaration of global variables, and definition of external functions is then tackled.

13. Using Schemas with XQuery - Provides a brief overview of XML Schema. Discusses how schemas are used with queries by importing schema definitions and taking advantage of schema-defined types.

14. Static Typing - Static typing in XQuery means reporting all possible type errors at compile time instead of run time. Discussed in the context of aggressive error reporting.

15. Principles of Query Design - Discusses the goals of query design with particular attention paid to handling errors and tuning for performance.

16. Working with Numbers - Describes the four major numeric types, along with the operators and functions that act on numeric values. The operators include comparisons and arithmetic operations. The functions that operate on numeric values that are discussed include round and sum.

17. Working with Strings - Discusses constructing and comparing strings and provides an overview of the built-in functions that manipulate strings. It also explains related features such as whitespace handling and internationalization.

18. Regular Expressions - Probably already a familiar concept to the Unix-aware, this discusses the topic in context of the XQuery language.

19. Working with Dates, Times, and Durations - Explains the eleven date-related types used in XQuery and the functions and operators that act on them.

20. Working with Qualified Names, URIs, and IDs - Each of these types has unique properties and complexities that sets it apart from simple strings. Describes the functions and constructors that act on them.

21. Working with Other XML Components - Discusses comments, processing instructions, documents, and text nodes. CDATA sections and XML character and entity references are also covered in this chapter.

22. Additional XQuery-Related Standards - Discusses serialization, XQueryX, XQuery Updates, Full-Text search, and XQJ. These are peripheral standards that complement, but are not central to, the XQuery 1.0 language.

23. Implementation-Specific Features - Looks at some of the implementation-specific aspects of XQuery that provide customized functions and settings for specific use cases.

24. XQuery for SQL Users - Provides information for readers who are already using SQL and relational databases. It compares SQL and XQuery and also shows how to use them together.

25. XQuery for XSLT Users - The similarities and differences between XQuery and XSLT. This chapter also shows XSLT 1.0/XPath 1.0 users the differences and compatibility problems when moving to XQuery/XPath 2.0.

A. Built-in Function Reference
B. Built-in Types
C. Error Summary

My first impression of this book is that it is fantastic. Just flip through the first chapter and you'll see references to code snippets and valuable explanations of XQuery. This book is what I was seeking. The author knows the reader has an interest in the subject and does not waste time explaining what XML is and why one would want to query it etc. This book is not selling the technology. It teaches it which is a lesson the author of "Querying XML" could learn from.

I am very happy thus far with this book.

XML programmers and database users will find Priscilla Walmsley's XQUERY a specific, valuable reference which is based on the Xquery 1.0 standards and which offers a basic tutorial on specifications and programming with the query language base. Query writers should have some knowledge of XML basics to use this, and can quickly progress into the 'advanced' category using an overview and tour of Xquery which includes guidelines for working with different types of data and an A-Z reference to the program's functions.

I had to learn XQuery and XForms in a rather limited time and this book helped me immensely. It has a very clear introduction, which gets you going and the rest of the chapters are sufficiently detailed to be useful. Very clear, full of code snippets. I wish a similar book was available for xForms :(

I'm using xquery within the eXist database and the code from this book work with eXist.

Excellent reference - I don't do any BDB XML work without it. The website has a ton of useful XQuery functions too. Outstanding work!

This is a nice, comprehensive book written by someone highly qualified to talk about XQuery. The author, Priscilla Walmsley, was a member of the W3C XML Schema Working Group.

Now that XML is being added to database management systems, DBAs and database developers will need to know how to query that data. And they'll more than likely be using XQuery to do it. As such, this book would be a good way for database professionals to gain expertise on XQuery.

Walmsley's book offers a concise, yet in-depth tutorial on the XQuery language specification. After digesting these 25 chapters you'll have the knowledge required to program using XQuery to read your XML data. Whether you're coming from a relational and SQL background or you're an XML and XSLT coder, this well-written text will help you understand and write queries using XQuery.

I needed to come up to speed with an XML database server (Mark Logic) and I found this book very useful for learning how to use XQuery. It was concise and provided many good examples. The presentation of chapters was somewhat episodic--you had to read the later chapters to find out how some of the topics turned out. This was probably due to the newness and complexity of the topic. I wouldn't be surprised if there was a chapter reorg for the 2nd edition.

In my case, the book covers only XQuery and does not cover the XQuery extensions and specifics of the XML database system I was using. Walmsley's book makes a great companion to the vendor documentation.

I did find this book extremely useful and have used it as my definitive reference for XQuery while working with real-world problems. The book was not only informative, comprehensive and filled with useful and easy to follow examples, but also realistic. You will find that any of the basic questions you have can be answered somewhere in this book (of course advanced questions often rely on the specific implementation, which is out of scope for the book and I recommend you hit online resources for those).

I do recommend reading/buying/using this book in your day-to-day work with XML in cooperation with an XQuery implementation. It's a little dry of information for advanced readers, but novice to intermediate readers will find it amazingly helpful.

However... this book has one major shortcoming: it is horribly written and organized.

The book seems to be written in a manner where the author knew exactly what they were talking about but didn't take the time to organize it or write a second and third draft. It feels like a "once-and-done" text and is inconsistent with coverage between all the various topics (for example: the structure of simple path queries is discussed sporadically while simple work with sorting and grouping is gone into a level of overkill in detail).

Good book to have on your shelf (just like the little SQL, Vi, Regex, etc. booklets we all have), but you've definitely got to break out the PostIt Notes to make sure you can find the information throughout the book.

It definitely needs more information here and there, but it's a great place to (at the least) start off and look for basic information.

The problem of this book is it doesn't give detailed information on how to implement X-Query on your computer. When you have Windows Vista, eXist doesn't work. Neither does WAMP. And unless you have heavy duty experience with SQL Server, this book is useless. The author of this book needs to include many more simple examples so that people like me can use the language. I might figure out how to use this someday, but it will be a long time before I do. That is so disappointing.