[SalesForce] How to add drill-down jQuery datatable in salesforce

Are you trying to get the value from the drop-down, or set the value? Because, from what I see from your code, you are using .val(value) which is a setter method, rather than .val() which is a getter method.

I.e.

// Gets the value from the selected option in the <select name="title"> element
var titleField = $dialogContent.find("select[name='title']").val();


// Sets the selected option in the <select name="title"> element
var doctorId = '00Ab00000057v4B';
$dialogContent.find("select[name='title']").val(doctorId);

Here is what you can do Create a custom button and fill in the details and in "Behavior Section" choose "Execute JavaScript" and for "Content Source" choose "OnClick JavaScript",and in the code section paste the following code

 
{!REQUIRESCRIPT("https://ajax.googleapis.com/ajax/libs/jquery/1.8.3/jquery.min.js")}
    function showSimpleDialog(){
   var sd = new SimpleDialog("Test"+Dialogs.getNextId(), true);

   sd.setTitle("Simple Dialog");

   sd.createDialog();

   window.parent.sd = sd;  sd.setWidth("50%");
  //Specify the iFrame and give URL of VF page
    sd.setContentInnerHTML("");


    if ($(sd.dialog).find('#InlineEditDialogX').size() == 0) {
    var close = $("<a id='InlineEditDialogX' title='Close' tabindex='0' href='javascript:void(0)' class='dialogClose'>Close</a>");

    close.mouseover(function() {

    this.className = 'dialogCloseOn';
    }).mouseout(function() {
    this.className = 'dialogClose';
    }).click(function() {

    // finally our on click handler which closes the dialog
    sd.hide();
    });
    // insert the new generated close button before the h2 tag so it'll show up on the top right corner
    close.insertBefore($(sd.dialog).find('.topLeft h2'));  
    } sd.show(); } showSimpleDialog();

This will bring up a modal where you can display your visual force page through iFrame and further through controller you can do all the DML operations.