如何在C＃Unity中通过php将Json Data发送到数据库

In Unity Game, I saved game data as Json data. and I tried to send Json data to php -> DB. when I directly put data in cform, it works.

So, I've used this code in my game and tried to send it to DB. But it doesn't work.

st2Manager

public class st2Manager : MonoBehaviour {

    string cAddress = "http://127.0.0.1/insertScore.php";

    void Start () {
        StartCoroutine(this.Call(cAddress));
    }

    // Update is called once per frame
    void Update () {

    }

    public IEnumerator Call(string _addres)
    {
        string score = Singleton.Instance.score.ToString();
        WWWForm cForm = new WWWForm();
        cForm.AddField("id", "kid");
        cForm.AddField("score", score);
        cForm.AddField("stage", "stage2");
        WWW wwwUrl = new WWW(_addres, cForm);
        yield return wwwUrl;
        Debug.Log(wwwUrl.text);
    }
}

PHP

<?php 
$con = mysql_connect("localhost","root","");
if($con){
    echo "Connect Success";
}else{
    echo "Connect Fail";
}
$id = @$_POST["id"];
$score = @$_POST["score"];
$stage = @$_POST["stage"];

echo "============";

echo $id;    
echo $score;
echo $stage;

mysql_select_db("choidb", $con);
mysql_query("INSERT INTO information (ID, Score, STAGE) VALUES ('$id', '$score', $'stage')");
echo "insert success";
?>

you didnt put a apostrophe correctly here: $'stage' in mysql_query("INSERT INTO information (ID, Score, STAGE) VALUES ('$id', '$score', $'stage')");