I worked with toools such as KARMA, D2RQ, Virtuoso.. It seems that all of them give new ontologies from a database, but not mapping the instances in ontology to a database so its values can get updated.

The only way that I could follow to map a RDB to let's say a customized ontology is using Jena framework. I could simply read the data from RDB using JAVA and import my ontology afterwards. In the next step, I could create the OWL instances and the final RDF dump by making use of Jena library. This may help --> (http://jena.apache.org/documentation/ontology/)

Basically, the mapping is the following

1) Database schema can be converted to a set of classes, datatype properties and object properties (TBox) 

• Table->class 
• Attribute->restriction on datatype property 
• foreign key->restriction on object property 

2) ABox:

• records (table rows) -> individuals of appropriate classes
• attribute values->literals linked by datatype properties corresponding to attribute names
• foreign key values -  assertions on relations between individuals  

I also suggest using Jena.

ontology structures is normally not supported in relational database system schema, because it consists of related tables of data , i would rather think of another database schema to represent ontologies , so instead using relational database think about using network database schema or hierarchal database schema

What do you mean by existing ontology, how is it represented ?

I think you should prefer to use a Graph Database (e.g. Neo4j) rather than a RDBMS. Because, graph databases are scheme-free.

I implemented the DAO pattern for my MA. You find it here:

https://github.com/uzuzjmd/Wissensmodellierung/tree/master/competence-database/src/main/scala/uzuzjmd/competence/owl/dao

Might not be easy to understand if you are not expert in Scala+Java+OWL

Piotr Szwed has right. 

Maybe these can also help:

• http://www.slideshare.net/rajighawi/db2owl
• http://test2010le2i.u-bourgogne.fr/le2i/IMG/publications/InterDB07-Ghawi.pdf (this is the paper from the presentation in the previous bullet)
• http://www.lu.lv/materiali/apgads/raksti/756_pp_99-117.pdf
• http://dl.acm.org/citation.cfm?id=2011263

Plz anyone who knows other way round help me???

that is how to save an ontology in database...i read with help of jena we can do that plz anybody who has done it give me the details??

@Manvi

1) To convert an ontology into a relational database (probably with some information loss) you must perform the mapping I described before.

2) However, an OWL ontology can be stored directly  in a database with Jena libraries: SDB (any relational database with JDBC) or TDB (own NOSQL format).

https://jena.apache.org/documentation/sdb/

http://jena.apache.org/documentation/tdb/

Both libraries work. An ontology is stored as RDF triples. The performance of SDB is rather poor. To access information on a class with several relations/attributes , the library makes a bunch of small queries for triples. They consume much time.

TDB performs much better, probably it is memory mapped.

Maybe you can be interested in Ontology-based Data Management (OBDM) and specifically in Ontology-based Data Access (OBDA). OBDA is a new paradigm in which an ontology is used to provide a formal representation of the domain of interest and is used for accessing the data. Topically in OBDA we have a three-level architecture in which we find the ontology, the data sources, and the mapping between the two. Users access external data by querying the ontology, without possessing knowledge on how the data is organized and where it is stored.

Here you can find more information about this approach:

http://wp.sigmod.org/?p=871

http://www.inf.unibz.it/~calvanese/papers/calv-etal-RW-2009.pdf

http://www.inf.unibz.it/~calvanese/papers/pogg-etal-JODS-2008.pdf

Two Ontology-based Data Access Systems are:

MASTRO:

http://151.100.59.93/~rosati/publications/Calvanese-etal-SW-11.pdf

http://www.vldb.org/pvldb/vol6/p1314-poggi.pdf

ONTOP:

http://www.dcs.bbk.ac.uk/~roman/papers/ISWC13.pdf

http://ontop.inf.unibz.it/

There is also a very active FP7 EU Project in which this technology is currently studied (http://www.optique-project.eu/)

Plz anyone knows how to reason from ontology for businesses rules compliance for templates parameters checking

You can read these articles about the relationship between models, enterprise architecture and ontologies:

https://caminao.blog/knowledge-architecture/ontologies-models/

https://caminao.blog/knowledge-architecture/ontologies-ea/

You may also have a look at the Caminao workbench built with Protégé/OWK 2:

https://webprotege.stanford.edu/#projects/e6c6b92b-cb9d-4919-9918-2596855e392b/edit/Classes

Maybe this helps a bit

https://mediatum.ub.tum.de/1392030

And see also the last two included publications.

yes well - I will take a look.