What tools exist for converting SQL scripts between different dialects ?

The ideal application I am looking for would be a GUI app with two textareas, and you would paste some SQL (DDL or DML) into one of the textareas, and then make a selection where you specify how the parser should try to comprehend that SQL, i.e. you might specify that the SQL in the textarea should be parsed as mySql dialect.
Then the other textarea should display the converted/generated SQL which is equivalent but written with a target dialect that you also should have specified.

If there is no such GUI based applications, but only some command line applicactions, e.g. ant tasks or some kind of reusable scripts for different conversions, then it would be better than nothing at least, i.e. better than manually trying to convert between dialects.

Do these kind of applications exist and is there any free such tools, and which ones are the best ?

/ Tom

I've seen many tools that will convert a GUI based query to different dialects of SQL, but I've never seen a usable tool to convert SQL code from one dialect to another. In some ways, this would be harder than natural language translation (English to Chinese for example).

If you find anything that can do even a mediocre job, I'd love to hear about it.

-PatP