JSP select onchange

<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>

<c:set var="abc" value=""></c:set>

<c:set var="att" value=""></c:set>

<c:set var="lat" value=""></c:set>

<c:set var="ear" value=""></c:set>

<c:if test="${b.att_checks ==0}">

<c:set var="abc" value="selected"></c:set>

 </c:if>

<c:if test="${b.att_checks ==1}">

<c:set var="att" value="selected"></c:set>

</c:if>

<c:if test="${b.att_checks ==2}">

<c:set var="lat" value="selected"></c:set>

</c:if>

<c:if test="${b.att_checks ==3}">

<c:set var="ear" value="selected"></c:set>

</c:if>

<form>

<select class="form-control" id="chk_att" onchange="location = this.options[this.selectedIndex].value;">

<option id="1" value="attendanceUpdate.do?user_id=${a.user_id }&att_date=${b.att_date}&att_checks=1"                                                  

${att }>출석</option>

<option id="0" value="attendanceUpdate.do?user_id=${a.user_id }&att_date=${b.att_date}&att_checks=0"

          ${abc }>결석</option>

      <option id="2" value="attendanceUpdate.do?user_id=${a.user_id }&att_date=${b.att_date}&att_checks=2"

${lat }>지각</option>

<option id="3" value="attendanceUpdate.do?user_id=${a.user_id }&att_date=${b.att_date}&att_checks=3"

${ear }>조퇴</option>

</select>

</form>