如何在未使用ID的下拉列表中加载值……隐藏所有已使用其值的记录？

Question

This shows all the records.Please help me to show only the records whose id is not used ..

<select name="userDetailId" class="form-control" required>
          <option value="">Select</option>

         <c:forEach items="${userDetailList}" var="userDetail">

         <option value="${userDetail.userDetailId}" <c:if test="${userDetail.userDetailId == dataMap.userDetailId}"> selected </c:if> >${userDetail.name}</option>

         </c:forEach>
     </select>

Answer 1

Create some flag let's say isUsed and populate it's value as either true/ false ie used or not and add similar condition as below.

<select name="userDetailId" class="form-control" required>
          <option value="">Select</option>

         <c:forEach items="${userDetailList}" var="userDetail">
<c:if test="${isUsed}"> 
         <option value="${userDetail.userDetailId}" <c:if test="${userDetail.userDetailId == dataMap.userDetailId}"> selected </c:if> >${userDetail.name}</option>
</c:if> 
         </c:forEach>
     </select>