NNDB is a C++ library that provides in-memory data storage and retrieval using syntax that is intended to feel natural for C++/STL, but which also might feel slightly like SQL if you squint and pound the top of your head with a seminal programming textbook. Columns types are fixed at compile-time and checked by the compiler.
iSfinx is a Web services based prototype of the Sfinx PIM. Sfinx is a personal knowledge and data manager which can manage your private data like contacts, events, notes, files, tasks, know-how, etc. Each data item is structured with abstract "slices", which are organized with a category hierarchy that you can define for your own needs. Every data item must be connected to some Sfinx object. Events can be connected to contacts, contacts to tasks, tasks to data sources, know-how, or notes, and so on. You can freely edit, delete, or reconnect them. Additional tags, which can be slices or other Sfinx objects, can also be attached to items, so any data you enter to Sfinx can be cross-connected with any other data or abstract category. A search engine helps you to navigate in this information ocean.