Abstract
One way to see the Semantic Web is to think of it as a set of all-knowing technologies that respond to whatever the user asks. The other view is that it is a set of standards and tools that help build better web applications.
Since the latter is probably more realistic at the moment, it means that a lot of software has to be developed before we start actually seeing the Semantic Web in widespread use.Many developers would be needed for the task and unless we 'win their hearts and minds', they are likely to obstruct rather than support the Semantic Web idea. And from the average developer's point of view, there is not much to like on today's RDF query languages, especially when compared with relational algebra and SQL.
Besides the fact that they are built on different principles, none of the languages we are aware of has a property that has served SQL so well - they are not closed.