急 ！！！！关于Jsp删除记录信息的问题，

<input type="button" class="login" value="保存" onClick="gotoupdate()" >
<input type="button" class="login" value="删除" onClick="gotodelete()" >
<%}else{%>
<input type="button" class="login" value="提交" onClick="gotosubmit()" >
<%}%>
<input type="button" class="login" value="返回" onClick="gotolist()" >
</center>
</form>

<script>
function gotosubmit(){
a.subtype.value="insert";
if(a.username.value==""){
alert("请您输入信息!");
a.username.focus();
return;
}

a.submit();
}
function gotoupdate(){
a.subtype.value="update";
a.submit();
}
function gotolist(){