How to send data form to server using json in unity

I want to using json to send the form to my server
here is my C# code

public string db_url="http://localhost/";
    IEnumerator SaveAllPlayerPrefs(object[] parms)
    	{
    		string ourPostData = "{\"bone\":\"42\"}";
    		
    		Hashtable headers = new Hashtable();
    		headers.Add("Content-Type", "application/json");
    		headers.Add("Cookie", "Our session cookie");
    		
    		byte[] pData = System.Text.Encoding.UTF8.GetBytes(ourPostData);
    
    		WWW webRequest = new WWW(db_url + "SaveAllPlayerPref.php", pData, headers);
    
    		yield return webRequest;
    	}

and here is my php code:

<?php
    $sql_connect = mysql_connect("localhost", "root", "") or die ("no DB Connection");
    
 mysql_select_db("example") or die ("DB not found");
    
    $bone = $_POST['bone'];  
    
    mysql_query("INSERT INTO save_game (bone) VALUES ('$bone');");

    mysql_close($sql_connect);
?>

When i run it this code its running, but when i check the database, its not save the value of bone. It’s save the empty string to bone, i want it to save 42…
in my database bone is varchar(100) and utf8_general_ci.

Can someone explain to me?
thx before:)

I’ve done for doing this below. Let’s go : ==>

using UnityEngine;

using UnityEngine.UI;

using System.Collections;

using System.Collections.Generic;

public class btnGetData : MonoBehaviour {

 void Start()
 {
     gameObject.GetComponent<Button>().onClick.AddListener(TaskOnClick);
 }
 IEnumerator WaitForWWW(WWW www)
 {
     yield return www;
    
     
     string txt = "";
     if (string.IsNullOrEmpty(www.error))
         txt = www.text;  //text of success
     else
         txt = www.error;  //error
     GameObject.Find("Txtdemo").GetComponent<Text>().text =  "++++++

" + txt;
}
void TaskOnClick()
{
try
{
GameObject.Find(“Txtdemo”).GetComponent().text = “starting…”;
string ourPostData = “{"plan":"TESTA02"”;
Dictionary<string,string> headers = new Dictionary<string, string>();
headers.Add(“Content-Type”, “application/json”);
//byte b = System.Text.Encoding.UTF8.GetBytes();
byte pData = System.Text.Encoding.ASCII.GetBytes(ourPostData.ToCharArray());
///POST by IIS hosting…
WWW api = new WWW(“http://192.168.1.120/si_aoi/api/total”, pData, headers);
///GET by IIS hosting…
///WWW api = new WWW(“http://192.168.1.120/si_aoi/api/total?dynamix={"plan":"TESTA02"”);
StartCoroutine(WaitForWWW(api));
}
catch (UnityException ex) { Debug.Log(ex.Message); }
}

}