我正在尝试使用ajax来编辑来自mysql的表。问题是这段代码在mysql数据库中返回null。我注意到它正确地找到了id，但是，当我提交时，其余的值没有被传输。
任何帮助都将不胜感激。
我有一个6列的表“id（int），license\u number（int），license\u type（varchar），trade\u name（varchar），cr\u num（int）”这是我的ajax：

<script>           
          var xmlhttp;
          if (window.XMLHttpRequest) {
              // code for IE7+, Firefox, Chrome, Opera, Safari
              xmlhttp=new XMLHttpRequest();
          } else { // code for IE6, IE5
              xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
          }

          function editData(str) {

            xmlhttp.onreadystatechange=function() {
              if (xmlhttp.readyState==4 && xmlhttp.status==200) {
                document.getElementById("info").innerHTML=xmlhttp.responseText;
                getData();
              }
            }
            var idx = str;
            var LICENSE_NUMBERx = document.getElementById("LICENSE_NUMBER-"+str).value;  // license_number
            var LICENSE_TYPEx = document.getElementById("LICENSE_TYPE-"+str).value;  // LICENSE_TYPE
            var TRADE_NAMEx = document.getElementById("TRADE_NAME-"+str).value;  // LICENSE_TYPE
            var CR_NUMx = document.getElementById("CR_NUM-"+str).value;  // CR_NUM
            //var dsx = encodeURIComponent(document.getElementById("ds-"+str).value);
            //var dtx = document.getElementById("dt-"+str).value;
            var params = "LICENSE_NUMBER="+LICENSE_NUMBERx+"&LICENSE_TYPE="+LICENSE_TYPEx+"&TRADE_NAME="+TRADE_NAMEx+"&CR_NUM="+CR_NUMx+"&id="+idx;

            xmlhttp.open("POST","projecteditdata.php");
            xmlhttp.setRequestHeader("Content-type","application/x-www-form-urlencoded");
            xmlhttp.send(params);
          }

          function deleteData(str) {

            xmlhttp.onreadystatechange=function() {
              if (xmlhttp.readyState==4 && xmlhttp.status==200) {
                document.getElementById("info").innerHTML=xmlhttp.responseText;
                getData();
              }
            }
            var idx = str;
            var params = "&id="+idx;

            xmlhttp.open("POST","projectdeletedata.php");
            xmlhttp.setRequestHeader("Content-type","application/x-www-form-urlencoded");
            xmlhttp.send(params);
          }

          function getData(){

            xmlhttp.onreadystatechange=function(){
              if (xmlhttp.readyState==4 && xmlhttp.status==200){
                document.getElementById("mytab").innerHTML=xmlhttp.responseText;
              }
            }
            xmlhttp.open("GET","projectgetdata.php",true);
            xmlhttp.send();
          }
    </script>

以下是sql：

$sql = "SELECT * FROM lcb_table WHERE ID IS NOT NULL ORDER BY LICENSE_NUMBER";
   /*$result = $conn->query($sql)*/
   $result = $conn->query($sql);

   echo "
   <table class='table table-bordered table-striped' id='tblData'>
      <thead>
         <tr>
            <th colspan='2'> Modifiy Record in Table </th>
            <th>License Number</th>
            <th>License Type</th>
            <th>Trade Name</th>
            <th>Central Registration Number CR</th>
         </tr>
      </thead>";
   // Loop through database
   while($row = $result->fetch_assoc()) {
      $id = $row['ID'];
      $license_number = $row['LICENSE_NUMBER'];
      $license_type = $row['LICENSE_TYPE'];
      $trade_name = $row['TRADE_NAME'];
      $cr_num = $row['CR_NUM'];
      echo   "
   <tbody>
      <tr>
       <td><button type='button' class='btn btn-warning btn-md active fa fa-pencil' data-toggle='modal' data-target='#update-" . $id . "'></button></td>
       <td><button type='button' class='btn btn-danger btn-md active fa fa-trash-o fa' data-toggle='modal' data-target='#delete-" . $id . "'></button></td>
       <td>".$license_number."</td>
       <td>".$license_type."</td>
       <td>".$trade_name."</td>
       <td>".$cr_num."</td>
      </tr>
   </tbody>";

下面是从projectgetdata.php调用它的表单

<div class="modal-body">
     <form>
         <fieldset>
       <div class='col-sm-2'>
           <div class="form-group">
              <label style="font-size: 12px" for="LICENSE_NUMBER">License Number</label>
              <input type="text" class="form-control" id="LICENSE_NUMBER-<?php echo $id ?>" value="<?php echo $license_number ?>">
           </div>
        </div>
       <div class='col-sm-2'>
           <div class="form-group">
             <label style="font-size: 12px" for="LICENSE_TYPE">License Type</label>
             <input type="text" class="form-control" id="LICENSE_TYPE-<?php echo $id ?>" value="<?php echo $license_number ?>">
           </div>
        </div>
       <div class='col-sm-8'>
           <div class="form-group">
             <label style="font-size: 12px" for="TRADE_NAME">Trade Name</label>
             <input name="TRADE_NAME" type="text" class="form-control" id="TRADE_NAME-<?php echo $id ?>" value="<?php echo $trade_name ?>">
           </div>
        </div>
       <div class='col-sm-4'>
           <div class="form-group">
             <label style="font-size: 12px" for="CR_NUM">Central Registration Number (CR)</label>
             <input name="CR_NUM" type="text" class="form-control" id="CR_NUM-<?php echo $id ?>" value="<?php echo $cr_num ?>">
           </div>
        </div>

       </fieldset>
     </form>

这里是projectedit.php端

<?php
include("../includes/config.php");
if ($conn->connect_errno) {
    echo "Failed to connect to MySQL: " . $conn->connect_error;
}
   $id = $_POST['ID'];
   $stmt = $conn->prepare("UPDATE lcb_table SET LICENSE_NUMBER=?,LICENSE_TYPE=?,TRADE_NAME=?,CR_NUM=? where ID=?");
   $stmt->bind_param('sssss', $license_number,$license_type,$trade_name,$cr_num,$id);
   $license_number = $POST['LICENSE_NUMBER'];
   $license_type = $POST['LICENSE_TYPE'];
   $trade_name = $POST['TRADE_NAME'];
   $cr_num = $POST['CR_NUM'];

   if($stmt->execute()){
    echo "Success";
    } else{
    echo "Error, No Data";
    }

$conn->close();
?>