simple select

HTML

<select id="brand_bu" name="selected" class="form-control">
                    <option value="1" selected>Please Select a Option..</option>
                    <option value="2">2</option>
                    <option value="3">3</option>
                    <option value="4">4</option>
                    <option value="5">5</option>
                    <option value="6">6</option>
                </select>
<span class="input-group-btn">
                        <button class="btn btn-primary" id="submit" type="button">Refresh Table</button>
                    </span>

<div id="show">I am show ID</div>
<div id="hide">I am hide ID</div>

JavaScript

$(document).ready(function(){

    $("#submit").prop("disabled",true);
    $("#hide").hide();
    $("#show").hide();
});

$("#brand_bu").change(function(){

    if($(this).val() != 1){
        $("#submit").prop("disabled",false);
    }
    else {
     $("#submit").prop("disabled",true);
    
    }

})

$("#submit").click(function(){
 $("#hide").show();
    $("#show").show();
})