<script>
function chkcid()
{
    if (document.form1.c_id.value=="")
{
alert("請先選擇第一个!")
form1.c_id.focus();
return false;
}
    }

</script>
<form id="form1" name="form1" method="POST" action="<%=MM_editAction%>">

       <select name="c_id" class="modelname" id="c_id">
              <option value="" selected="selected">請選擇</option>
              <option value="1">1</option>
              <option value="2">2</option>
            </select></td>
          <td>
            <select name="years" class="modelname" id="years" onchange="chkcid();">
              <option value="" selected="selected">請選擇</option>
              <option value="2012">2012</option>
              <option value="2013">2013</option>
              <option value="2014">2014</option>
              <option value="2015">2015</option>
              <option value="2016">2016</option>
            </select></td>
</form>