Get DB content into dropdown and show DB info from selected dropdown

as @WisdmLabs mentioned, you are on the right track...

The steps to continue shouls be:

1. Add a JS event once both dropboxes were selected (using onchange() or a submit button)

2. The event will fire an AJAX request for a PHP file with the POST data of the item you want to get the data for.

3. On the PHP file you will run your SQL query and send back the information needed- preferable as in json.

4. On the JS AJAX function you will get the Json object and inserted neede info into the page DOM

JS Code

$(".dropboxClass").change(function(){ // you can use a button instead or any other event type
    // here you can first check that bothdropboxes were selected 

    // now get the values of the dropboxes
    drop1 = $("#dropbox1").val();
    drop2 = $("#dropbox2").val();

    // run the AJAX request for the PHP file
    var request = $.ajax({
                    url: 'test2.php',
                    dataType: "json" ,
                    method: "POST",
            data: { d1: drop1, d2:drop2 } 
                });

        request.done(function(itemData){
            // here you will get the Json object , get the data you need and insert into the DOM
            console.log('Status:' + itemData['status']);
            console.log('Name:' + itemData['name']);

            alert('success');
        });

        request.fail(function(){
            // AJAX call failed - do something.....
        });
});

PHP Script

// connect to your DB and get the data you need into an array 

$DB_data = array(
    "status"=>"code",
    "name"=>"item Name",
    "desc"=>"Item Description"
);

echo json_encode($DB_data);