SQL Workbench/J is a free, DBMS-independent, cross-platform SQL query tool. It is written in Java and should run on any operating system that provides a Java Runtime Environment.
Its main focus is on running SQL scripts (either interactively or as a batch) and export/import features. Graphical query building or more advanced DBA tasks are not the focus and are not planned
Project has custom version of Apache license that _forbids_ certain governments from use: