Entity Extractor is an application that generates ORM code from a database structure. It was originally written for generating class codes for Storm (The Canonical ORM for Python), but can be extended to generate ORM code from almost any database type. It is highly configurable, has a simple interface, and allows users to add their own features very easily.
ODB is a compiler-based object-relational mapping (ORM) system for C++. It allows you to persist C++ objects to a relational database without having to deal with tables, columns, or SQL and without manually writing any mapping code. The C++ code that performs the conversion between persistent classes and their database representation is automatically generated by the ODB compiler. The ODB compiler is a real C++ compiler except that instead of producing assembly or machine code, it generates portable C++, which can in turn be compiled by any C++ compiler. ODB is not a framework. It does not dictate how you should write your application. Rather, it is designed to fit into your style and architecture by only handling C++ object persistence and not interfering with any other functionality.
OOS is a C++ object-relational mapping (ORM) framework. It aims to encapsulate all of the database backend functionality and keep it away from the user. One don't have to deal with database backends or SQL statements, nor with mapping of data types or serialization of objects. It provides an STL-like API and one container for all persistent objects - the object store.