Mapping SQL Data to RDF

Introduction

Virtuoso uses a SPARQL-based Meta Schema Language to provide RDBMS-to-RDF mapping functionality (also described as, RDF Views of SQL data). The language is an extension of the SPARQL query language meshed with Virtuoso's SPASQL (SPARQL-inside-SQL) functionality. The language enables you to declaratively map relational database schema tables, columns, rows, and foreign key relationships to Classes, Attributes, Relationships, and Instances (Objects/Entities/Individuals) defined by RDF Schemas or OWL Ontologies. The mapping process uses a special built-in Virtuoso function to generate IRIs / URIs in "Subject" or "Object" position of a SPARQL graph pattern, en route to building a set of SQL compiler rules and optimizations for translating SPARQL queries into SQL on the fly.

Mapping Process

The basic steps are as follows:

1. Identify the tables, views, and procedure views to be mapped.
2. Decide if you are performing a 1:1 mapping or a more customized mapping to a specific RDF Schema or Ontology.
3. Declare Virtuoso-URI-Generator functions for each Class in the target RDF Schema or Ontology.
4. Use the Virtuoso-URI-Generator functions in SPARQL graph patterns within the ALTER QUAD STORAGE part of a SPASQL-based mapping statement.
5. Use Virtuoso's built-in URL-Rewrite Rules APIs (or Conductor UI) to publish the Linked Data URIs which result from the mapping above.

Mapping Example

• View an example of mapping the phpBB3 SQL schema to the classes defined by the SIOC and FOAF ontologies.

Linking Remote tables into Virtuoso Examples

• View how to perform linking across all Virtuoso supported mechanisms i.e. for Oracle, SQL Server, DB2, Sybase, Informix, Ingres, MySQL, PostgreSQL, ODBC, and JDBC DSNs.

White Papers & Tutorials

• Declarative Meta Schema Language for SQL Schema to RDF Ontology Mapping - White Paper
• Declarative Meta Schema Language for SQL Schema to RDF Ontology Mapping - Tutorial

Generation of RDF Views from SQL data

Automated Generation of RDF Views over Relational Data Sources

• Automated Generation of RDF Views

Sample Mapping Scripts

Web 2.0 Platforms

• phpBB3 to RDF
• Wordpress to RDF
• MediaWiki to RDF
• Drupal to RDF
• Bugzilla to RDF

Semi-Structured Content Examples

• Virtuoso Product Documentation (DocBook) to RDF
• Virtuoso Online Tutorials to RDF

Enterprise Data Access & Integration

• Virtuoso's Northwind based Demo Database (Tutorials variant) to RDF
• SQL Server's Northwind Demo Database
• Oracle using the demonstration 'Human Resources' database
• DB2 using the demonstration 'Sample' database
• Informix using demonstration 'Stores' database
• Ingres using demonstration 'Tutorial' database
• Sybase using demonstration 'pubs2' database
• Progress (SQL-89) using demonstration 'iSports' database
• Progress (SQL-92) using demonstration 'iSports' database
• BSBM to RDF

ODS Applications RDF Views

• ODS RDF Views
• eCRM Views

Business Intelligence

• TPCH to RDF
• TPCD to RDF
• Thalia to RDF
• Musicbrainz to RDF

How Do I ...?

• ...Use SPARQL to Query Virtuoso's Online Tutorials Data Space
• ...Use SPARQL to Query Virtuoso's Online Documentation Data Space
• ...Use SPARQL to Query the Northwind SQL-RDF Linked Data
• ...Use SPARQL to Query the WordPress SQL-RDF Linked Data
• ...Use SPARQL to Query the MedaWiki SQL-RDF Linked Data
• ...Use SPARQL to Query the PHPBB SQL-RDF Linked Data

Screencast Demos

• Virtuoso RDF Views over RDBMS Data Sources - Part 1
• Virtuoso RDF Views over RDBMS Data Sources - Part 2