I'm going to develop a samsung smart tv app, but I don't know how to make request in server db because samsung smart tv supports only Javascript.
You can't access the database directly. You need to create a web service. Your server will accept HTTP requests, run a piece of software (e.g. written in Perl or PHP) and return the data in the response.
Samsung provides an implementation of XMLHttpRequest. You can use this to cause the device to make the HTTP requests.
They have an example of how to use it in their SDK documentation.