SPARQL (pronounced "sparkle", acronym for Simple Protocol And RDF Query Language) is an RDF query language, that is, a semantic query language for databases. With SPARQL you can extract any kind of data, with a query composed of logical combinations of triples.
Wikidata provides an SPARQL endpoint including a powerful Web-GUI since September 2015.
This book focusses on the Wikidata database, with lots of examples
- Filtering: FILTER, FILTER NOT EXIST and MINUS
- Modifiers like GROUP BY, HAVING, ORDER BY, LIMIT
- Bad aggregate error
- Aggregate functions COUNT, MIN, MAX, SUM, AVG, SAMPLE and GROUP_CONCAT
Advanced SPARQL topics
WIKIDATA data representation
- WIKIDATA Qualifiers, References and Ranks
- WIKIDATA Language links and Badges
- WIKIDATA Precision, Units and Coordinates
- Query optimization (and hint:Query hint:optimizer)