KDb is a database connectivity and creation framework for various database vendors.
KDb is consisted of a general-purpose C++/Qt-only library and a set of plugins. Because there is no dependency on Kexi, Calligra or even on KDE libraries, KDb is developed for a wider audience. Kexi since the version 3 uses it too, thus deprecating KexiDB.
Unlike QtSQL, KDb 'knows' how to create database and new tables. It has a Qt/C++ API for that. There is no need to pass SQL at all but you can pass if you wish (it will silently parse your statements before contacting the database). KDb is developed as a next generation database handling layer for Kexi and similar complex apps.
KDb is widely free/libre software available under the GNU Lesser General Public License (LGPL). Thus, developers are free to:
KDb is a new iteration of library developed since 2003 within. It was previously known as KexiDB. Together with Kexi application, development is organized together with the Calligra Suite (formerly KOffice) project but KDb's release schedule is separate and there is no technical dependency on Calligra applications or frameworks.