Foreword
Companies come and go in the database industry, but one thing remains constant: Jim Melton remains at the center of the database standards community. For more years than anyone cares to remember, Jim has served as editor of the international standard for the SQL database language. Perhaps more importantly, he has translated this standard into terminology that ordinary people can understand and has made it accessible to everyone in a series of successful books.
Now the database world is undergoing its most important transition since the advent of the relational data model in the 1970’s. A new self-describing data format, XML, is emerging as the standard format for exchange of semi-structured data on the Web. XML is fundamentally different from relations because it carries descriptive metadata with each data instance rather than storing it in a separate catalog. This new format gives unprecedented flexibility for representing various types of data but at the same time it requires a new approach to query.
A collection of query-related standards is emerging around the XML data format, and as usual Jim Melton is at the center of the action. Jim is co-chair of the W3C XML Query Working Group, which is creating an important new language called XQuery and (together with the XSLT Working Group) is revising the well-known XPath language. Jim is also co-Spec Lead for XQJ, the Java interface to XQuery that is being developed under the Java Community Process. In addition, as editor of the SQL Standard, Jim serves as editor of SQL/XML, the set of SQL extensions that enable relational databases to store and query XML data.
Stephen Buxton is also a long-time member of the W3C XML Query Working Group, and a specialist in full-text search and retrieval. Stephen’s expertise in approximate queries on unstructured text complements Jim’s long experience with exact queries on structured data.
In short, there is no more authoritative pair of authors on Querying XML than Jim Melton and Stephen Buxton. Best of all, as readers of Jim’s other books know, his informal writing style will teach you what you need to know about this complex subject without giving you a headache. If you need a comprehensive and accessible overview of Querying XML, this is the book you have been waiting for.