php ajax如何实现批量删除

$("#cq").click(function () {
 $(".cq").prop("checked", $(this).prop("checked"));
})

var chk = "";
var check2 = ""; //判断多个复选框中的某一个是否被全选
function checked() {
 var count = 0;
 var checkx = $("#cq");
 if (checkx.checked) {
 check2 = 1;//选中全选按钮
 } else {
 check2 = 0;//没选中全选按钮
 }
 var checkArry = $(".cq");
 for (var i = 0; i < checkArry.length; i++) {
 if (checkArry[i].checked == true) { //选中的操作
 count++;
 }
 }
 if (count == 0) {
 chk = 0;//没有选中项
 } else {
 chk = 1;//有选中项
 }
}
function all() {
 //批量删除
 $("#plscdz").click(function () {
 checked();
 if (chk == 1 || check2 == 1) {// 提交
 $('#myModal12').modal('show');
 $("#nqrplsc").click(function () {/*给确认删除按钮加事件*/
 $('#myModal12').modal('hide');
 //找选中的主键值，用循环遍历选中的主键值
 var cq = $(".cq");
 var plstr = "";
 for (var i = 0; i < cq.length; i++) {
 if (cq.eq(i).prop("checked")) {
 plstr += cq.eq(i).val() + "','";
 }
 }
 plstr = plstr.substr(0, plstr.length - 3);
 //分隔符占3个字符，截取字符串，去掉最后的"','"
 $.ajax({
 async: false,
 url: "aa.php",
 data: {id: plstr},
 dataType: "TEXT",
 type: "POST",
 success: function (data) {
 if (data.trim() == "OK") {
 alert("删除成功");
 } else {
 alert("删除失败");
 }
 }
 });
 });
 } else if (chk == 0) {
 alert("请选择您要删除的内容");
 }
 })
}

session_start();
include("DBDA.class.php");
$db = new DBDA();
if (!empty($_POST["id"])) {
 $id = $_POST["id"];
 $sql = "delete from user where id in ('{$id}')";
 if ($db->Query($sql, 0)) {
 echo "OK";
 } else {
 echo "NO";
 }
}