SPARQL (pronounced "sparkle", acronym for SPARQL 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 focuses on the Wikidata database, with lots of examples.
Other SPARQL endpoints include SOPHOX which use the same GUI as Wikidata SPARQL Service for OpenStreetMap and Wikidata.
- Filtering: FILTER, FILTER NOT EXIST and MINUS
- Modifiers like GROUP BY, HAVING, ORDER BY, LIMIT
- Aggregate functions COUNT, MIN, MAX, SUM, AVG, SAMPLE and GROUP_CONCAT
- Bad aggregate error
Advanced SPARQL topics
- Property paths and Instances and classes
- Expressions and Functions
- Federated query
WIKIDATA data representation
- WIKIDATA Qualifiers, References and Ranks
- WIKIDATA Language links and Badges
- WIKIDATA Precision, Units and Coordinates
- WIKIDATA Lexicographical data
- Wikimedia Commons Query Service