I had some issues with DbVisualizer and auto commit. I wanted to be able to turn it off from the SQL commander. The official documentation states that you can do this using:

The Auto Commit setting is enabled by default and can be adjusted in the Connection Properties. You may also adjust the  auto commit state for the SQL editor you are using in the SQL Commander with the following command:

@set autocommit true/false

Unfortunately this didn’t work for  me in either 6.5.12 or 7.04 (I’m using OS X and Java 6) against an Oracle 10g database. I get an error alert stating “/application/set autocommit false (No such file or directory)”
I was finally able to figure out that you can get it to work using:

@set autocommit off/on

I’m not sure if this is a problem that only occur on OS X.