Javascript 如何将单选按钮的值插入数据库？

我有以下代码：

<label style="cursor:pointer;"><input type="radio" name="rads" value="'.$correct.'" id = "radio">'.$answer.'</label> 
<button onclick="myFunction()">Value</button>';

但只有“错误”列在递增。我尝试使用js打印所选单选按钮的值：

<p id =" demo"></p>
<script>
function myFunction() {
    var x = document.getElementById("radio").value;
    document.getElementById("demo").innerHTML = x;
}
</script>

函数myFunction（）{
var x=document.getElementById（“radio”）.value；
document.getElementById（“demo”）.innerHTML=x；
}

但当我点击按钮时，什么也没有出现。我还尝试：

var try = document.getElementsByName('rads');
for (var i = 0, len = try.length; i < length; i++) {
if (try[i].checked == 0) {
    // increment wrong in db

    else if (try[i].checked == 1){
        //increment correct in db
    }

    break;

}

var try=document.getElementsByName（'rads'）；
for（变量i=0，len=try.length；i

我真的不知道该怎么办了。如果我不清楚，很抱歉。

试试这段代码

var try = document.getElementsByName('rads');
   for (var i = 0, len = try.length; i < length; i++) {
   if  !(try[i].checked) {
   // increment wrong in db

   else if (try[i].checked){
    //increment correct in db
  }

  break;

  }

var try=document.getElementsByName（'rads'）；
for（变量i=0，len=try.length；i

我无法清楚地理解您的问题，我从您的代码中发现了一个错误

<label style="cursor:pointer;">
  <input type="radio" name="rads" value="<?php echo $correct; ?>" id = "radio"><?php echo $answer; ?></label> 
<button onclick="myFunction()">Value</button>';

经过多次尝试和错误，下面的代码终于对我起到了作用。我添加了ajax函数，单选按钮在该函数下单击时调用

<script>
function addVote(str) {
if (str == "") {
    document.getElementById("txtHint").innerHTML = "";
    return;
} else {
    if (window.XMLHttpRequest) {
        // code for IE7+, Firefox, Chrome, Opera, Safari
        xmlhttp = new XMLHttpRequest();
    } else {
        // code for IE6, IE5
        xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
    }
    xmlhttp.onreadystatechange = function() {
        if (xmlhttp.readyState == 4 && xmlhttp.status == 200) {
            document.getElementById("txtHint").innerHTML = xmlhttp.responseText;
        }
    }
    xmlhttp.open("GET","try.php?rad="+str,true);
    xmlhttp.send();
    }
}

    </script>

 <?php
$q = $_GET['rad'];

$con = mysqli_connect('localhost','','','try');
if (!$con) {
    die('Could not connect: ' . mysqli_error($con));
}

mysqli_select_db($con, 'try');
if($q == 1){
$sql="UPDATE count SET correct = correct+1, wrong=wrong+0 WHERE question_id = 1 ";
} else{
$sql="UPDATE count SET correct=correct+0, wrong=wrong+1 WHERE question_id = 1 ";
}
$result = mysqli_query($con,$sql);


mysqli_close($con);
?>

我认为这不起作用，因为用户必须单击按钮才能在数据库中更新值。
if！（请尝试[I]。选中）
这可能不起作用。
 <?php
$q = $_GET['rad'];

$con = mysqli_connect('localhost','','','try');
if (!$con) {
    die('Could not connect: ' . mysqli_error($con));
}

mysqli_select_db($con, 'try');
if($q == 1){
$sql="UPDATE count SET correct = correct+1, wrong=wrong+0 WHERE question_id = 1 ";
} else{
$sql="UPDATE count SET correct=correct+0, wrong=wrong+1 WHERE question_id = 1 ";
}
$result = mysqli_query($con,$sql);


mysqli_close($con);
?>

onclick="addVote(this.value)"