SPARQL (Recursive acronym for SPARQL Protocol and RDF Query Language) is an RDF query language—that is, a semantic query language for databases—able to retrieve and manipulate data stored in RDF format.

In the wiki, SPARQL powers wiki query, inline tables refreshed by wiki render, and (when enabled) a read-only HTTP endpoint on wiki serve.

Common prefixes

The wiki automatically binds your namespace prefixes dynamically from the wiki.yaml file. The primary prefix mappings are:

• schema: https://schema.org/ (Standard schema vocabulary)
• wiki: https://wazootech.github.io/wiki/wiki/ (Your local wiki namespace)
• rdf: http://www.w3.org/1999/02/22-rdf-syntax-ns# (Standard RDF attributes)

Example query types

Simple SELECT query

Extracts specific properties from your notes. For people, prefer schema:givenName and schema:familyName (see Style Guide):

PREFIX schema: <https://schema.org/>
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>

SELECT ?person ?given ?family WHERE {
  ?person rdf:type schema:Person .
  ?person schema:givenName ?given .
  ?person schema:familyName ?family .
}

Filtered query

Uses standard string or URI filters to constrain your results. For TechArticle pages, schema:headline and schema:description are the display fields:

PREFIX schema: <https://schema.org/>

SELECT ?doc ?headline ?description WHERE {
  ?doc rdf:type schema:TechArticle .
  ?doc schema:headline ?headline .
  OPTIONAL { ?doc schema:description ?description . }
  FILTER(STRSTARTS(STR(?doc), "https://wazootech.github.io/wiki/wiki/"))
}

Active database summary

The table below queries the active graph to list all distinct classes currently instantiated in your wiki:

PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>

SELECT DISTINCT ?class WHERE {
  ?s rdf:type ?class .
  FILTER(STRSTARTS(STR(?class), "https://schema.org/"))
}
ORDER BY ?class

Related

• wiki query — ad-hoc queries from the terminal
• wiki render — refresh inline SPARQL result tables in markdown
• wiki serve — optional read-only HTTP endpoint on wiki serve
• wiki-templates/yasgui — external YASGUI template repository (Wiki CLI templates)
• Style Guide — sparql:start / sparql:end block conventions

References

• SPARQL 1.1 Query Language: Query language for RDF graphs.