You cannot call mySQL calls with JavaScript directly.. unless you are using something like nodejs, but I don't recommend this sort of development (and not even sure if you can leverage that via Launch anyway)...
If you need data, you should be working with your developers to have then create a data layer on the site that you can read. Usually this will be a JS Object that is available to the window, that is populated in JSON format... You will have to work with your team to understand what type of info you want/need and make it available.
