Object-relational database articles and products

Object-relational database management systems span object and relational technology. Most products adhere to the SQL:1999 standard, but some provide a proprietary approach. This site provides articles and a product listing for object-relational databases.

Why "object-relational?"

Essentially, the SQL:1999 object model has all the same features as the object model used by object database management systems (ODBMSs), but in a way different from most ODBMSs. This was caused by the mandate that SQL:1999 be backward compatible to SQL-92. That mandate required adapting the SQL:1999 object model to the SQL-92 relational model. As a result, the SQL:1999 object model does not match the object model used by object programming languages. The term object-oriented cannot be used to describe this model because that would imply that the database models match object programming models. Instead, the term object-relational is used.

SQL:1999 expands the data complexity and performance capability of relational databases with the object structures that were added. Nevertheless, more complex structures that can be used by an object programming language will result in impedance mismatch and require mapping. The mapping, however, is not as complicated as it is for SQL-92 RDBMSs. The data mapping is needed to move data from a database to an object programming language (or an application server using an object programming language) and additional mapping to move the data back to the database. (ODBMSs that use the same object model as object programming languages do not need this type of mapping.) More information on mapping and impedance mismatch can be found in the articles mentioned in the next section.

A common initialism used for an object- relational database management systems is ORDBMS.

Articles

Object-relational databases blend relational and object technology. Related topics at this site include:

DBMS concepts and standards

ODBMSs

Impedance mismatch

Mapping

OR mapping

RDBMSs

Products

Vendors are listed on this site with links to their respective Web sites. See the Web sites for object-relational database products.

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Not necessarily object-relational

	C# DBMSs
	C++ DBMSs
	Java DBMSs