text: 9.2 SPARQL Queries 
  SPARQL is a powerful language, and one could write a whole book about it. In fact, there are books 
  written about it. The best one I have seen is the O’Reilly book Learning SPARQL by Bob DuCharme. 
  This is an excellent book that not only goes into SPARQL but into topics such as RDF/RDFS and how 
  triples are used to represent all information in OWL. I will only touch on those issues here, there is much 
  more to say about them and DuCharme’s book is a great place to learn more. If some of the following is a 
  bit hard to understand don’t be discouraged. This is just an attempt to give a very high level introduction 
  to something that requires significant study to really understand. 
  
  Essentially SPARQL is to the Semantic Web and Knowledge Graphs as SQL is to relational databases. 
  Just as SQL can do more than just query, it can also assert new information into a database, so SPARQL 
  can as well. The current SPARQL plugins for Protégé are somewhat limited and don’t support the 
  statements such as INSERT for entering new data so we will just cover the basics of using SPARQL as a 
  query language but keep in mind there is a lot more to it than what we briefly cover here. 