jquery change attr href with value from select

 <div id="select_1">

<select class="select-class">
    <option value="value_1" selected="selected">1</option>
    <option value="value_2">2</option>
    <option value="value_3">3</option>
</select>
<a href="#" class="a-class">Link</a> 
</div> 

<div id="select_2">
<select class="select-class">
    <option value="value_1">1</option>
    <option value="value_2" selected="selected">2</option>
    <option value="value_3">3</option>
</select>
<a href="#" class="a-class">Link</a> 
</div>

<div id="select_3">
<select class="select-class">
    <option value="value_1" selected="selected">1</option>
    <option value="value_2">2</option>
    <option value="value_3">3</option>
</select>
<a href="#" class="a-class">Link</a> 
</div>

======================================================================

$(function() {
    $("select.select-class").on("change", function() {
        var link = $(this).parent().find("a.a-class");
        link.attr("href", "url.com?" + $(this).val());
    });
}