GUI tools that have not been mentioned here, that I know work under Linux without WINE:
- DBeaver https://dbeaver.io/ (Java, GPL)
- Squirrel http://www.squirrelsql.org/ (Java, LGPL or GPL)
- ocelotgui https://github.com/ocelot-inc/ocelotgui (C++, GPL)
Disclosure: I work for Ocelot.