# TODO: See https://www.w3.org/TR/r2rml/
# This document describes R2RML, a language for expressing customized mappings from relational databases to RDF datasets.
# Such mappings provide the ability to view existing relational data in the RDF data model,
# expressed in a structure and target vocabulary of the mapping author's choice.
# R2RML mappings are themselves RDF graphs and written down in Turtle syntax.
# R2RML enables different types of mapping implementations.
# Processors could, for example, offer a virtual SPARQL endpoint over the mapped relational data,
# or generate RDF dumps, or offer a Linked Data interface.

# http://d2rq.org/
# Accessing Relational Databases as Virtual RDF Graphs

# These projects seem inactive (2020)
# Both need a mapping language: It is better to build an ontology
# just out of the database, with no extra information.

# TODO: Create an ontology out of a database:
# Each table is an object type.
# Each row is an object.
# One needs an unique id for each row: Oracle offers this,
# or an unique index.
# Each cell defines a triple.
# A foreign index defines an object of a triple, instead of a literal value.