While some products exist out there which do exactly that, they are mostly not well integrated or only work for earlier visual studio versions.
I think that such a GUI could add yet another selling point to your product. Besides features of managing table structures and table data, something that as far as I am aware has never been done before, would be to have a query builder which in full automatiion generates the query and the php code to get the data.

For example, when using that function, a class is needed for the application. This class is automatically placed in the project. After that the user graphically decides what data he wants to pull of the database (query builder). Once the query is test executed to see if the desired results are achieved, the plugin would generate PHP code using the previously mentioned class and place it automatically in the currently opened file. Perhaps some options as how to save the data would be useful too (array / string...).

Just a suggestion, might as well be far overshot.

Regards,
max