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GCN Home > 03/21/05 issue

SQL vs. XML in a database world

By Joab Jackson, GCN Staff

In a sense, Jonathan Robie acts as a diplomat between two disparate technologies—Extensible Markup Language and relational databases. Communicating between those two worlds is not a task for the faint-hearted. Advocates of the Structured Query Language, which allows users to access information in relational databases, are quick to point out XML’s deficiencies, while XML adherents question the value of a relational model.

Robie seeks to bridge these two worlds. He is one of the chief authors of XQuery, an SQL-like query language that can be used for searching both XML documents and relational databases. The World Wide Web Consortium, the international body that creates and maintains Web standards, is now reviewing XQuery as a formal draft.

In addition to XQuery, Robie works on a number of other W3C working groups and is co-author of XQuery from the Experts, published by Addison-Wesley. In his day job, he’s the XML program manager at data connectivity software provider DataDirect Technologies Inc. of Bedford, Mass. Previously, Robie was an XML Research Specialist at Software AG. He spoke to GCN associate writer Joab Jackson by phone.

GCN: How is XQuery different from Structured Query Language?

ROBIE: SQL is a relational query language, XQuery is an Extensible Markup Language query language. If all you are doing is querying relational databases, then SQL is the language you want. XQuery works best if you’re querying XML or a combination of XML and relational sources.

GCN: How did you first start working with XML? Did you know it would consume a large portion of your career when you started?

ROBIE: No. I was working for an object database company at the time [1995] and a medical textbook publisher contacted us, wanting a Standard Generalized Markup Language database.

That was before XML. Since I was the person who knew the most acronyms in the company, the call was put through to me.

I spent a lot of my career working with things that do not fit naturally into relational databases—geographic information systems, multimedia systems or things like that.

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