Kexi is an open source software project distributed as part of the popular Calligra office suite and designed to act as a visual database creator.
Kexi was designed as a way of creating databases visually, using a system that is very similar to that used by other applications like Microsoft Access, FileMaker or even Base.
The application comes with built-in support for the SQLite, MySQL and PostgreSQL database servers, allowing the user to store and share all the design and data.
No installation or maintenance is required.
Therefore, if you want to have the best tool to create databases for KDE, you only have to download Kexi for free.