The Kompany, known for its products for KDE, has released Rekall under the GPL. Rekall is like Microsoft Access, but it works with MySQL and PostreSQL (DB2 as well, but no Oracle yet). So, you get the form builder capability and easy import/export. It is scriptable with Python. They’ve set up a site called Rekall Revealed to host the open source project. Rekall does not rely on KDE, but will run on Windows and Linux using Qt.
There is also a runtime available that appears to be less restricted than the GPLed main product. I’d be curious to give it a try. Looks pretty spiffy from the screen shots.