Tool to convert Relational Database to RDF

The D2RQ Platform is a system for accessing relational databases as virtual, read-only RDF graphs. It offers RDF-based access to the content of relational databases without having to replicate it into an RDF store. Also D2RQ is open source software licensed under Apache license. D2RQ support databases such as Oracle, SQL Server, PostgreSQL, MySQL or HSQLDB etc.

Using D2RQ one can,

• query a non-RDF database using SPARQL
• access the content of the database as Linked Data over the Web
• create custom dumps of the database in RDF formats for loading into an RDF store
• access information in a non-RDF database using the Apache Jena API

D2R Server can be run either as a stand-alone web server or inside an existing servlet container.

To map the Relational Database to RDF a mapping file is used. This mapping file can be created manually or using generate-mapping tool that generates a skeleton “default mapping” from the database schema automatically. Creating mapping file using generate-mapping tool is much faster than manually creating the mapping file.

The mapping defines a virtual RDF graph that contains information from the database. This is similar to the concept of views in SQL, except that the virtual data structure is an RDF graph instead of a virtual relational table. The virtual RDF graph can be accessed in various ways, depending on what's offered by the implementation. The D2RQ Platform provides SPARQL access, a Linked Data server, an RDF dump generator, a simple HTML interface, and Jena API access to D2RQ-mapped databases.