如何在下拉列表中选择选项之前隐藏单选按钮？

When a option is selected in drop down it shows data from mysql and I need it to be selectable. So I made a radio button but I need it to appear after option is selected but instead it is always there.

Let your radiobuttons div have the id of "radio_div" and your select - "select_options", then:

document.getElementById('select_options').addEventListener('change', function () {
    document.getElementById('radio_div').style.display = 'block';
});

Not sure if I understand, but something like this?

http://jsfiddle.net/zysrcndx/

HTML:

<select id="show">
  <option value="no" selected="selected">not showing</option>
  <option value="yes">showing</option>
</select>

<div id="radio" style="display: none;">
  <input type="radio" name="radio" value="something">Something<br>
  <input type="radio" name="radio" value="somethingelse">Something Else
</div>

JavaScript:

var dd = document.getElementById('show');
var r = document.getElementById('radio');

dd.addEventListener('change', function () {
        if(dd.options[dd.selectedIndex].value == 'no') {
        r.style.display = 'none';
    } else {
        r.style.display = 'block';
    }
});