Al Stevens has written a book on the subject called 'Database programming in C++' or something. An article on the subject was printed in Doctor Dobbs Journal some time ago.
The nice thing is that Stevens also wrote a C++ library adding persistence to C++, and the source is available. The library is called PARODY and compiles under most DOS-based C++ compilers. A slight rewrite of the GUI- routines has to be done to make it compile under GNU C.
ftp from ftp.mv.com in pub/ddj/1992.12/parody.zip pub/ddj/1992.12/parody.dir (directory of zip)