MySql data using JSON and AJAX in PHP - php

Question

I want to get searched data from mysql database using JSON and show in my php page. I was write this code but it not retrieve any data.please help me
Client page
$(function () {
var roll = document.getElementById("roll").value;
$.ajax({
type: "POST",
url: 'api.php',
data: "roll=" + roll,
dataType: 'json',
success: function (data) {
var id = data[0];
var vname = data[1];`$` ('#output').html("id: " + id + " name: " + vname);
}
});
});
api.php
$host = "localhost";
$user = "root";
$pass = "";
$databaseName = "ajax";
$tableName = "stud";
$con = mysql_connect($host,$user,$pass);
$dbs = mysql_select_db($databaseName, $con);
if(isset($_POST['roll'])){
$data = $_POST['roll'];
$result = mysql_query("SELECT * FROM $tableName WHERE roll = '".$data."'");
$array = mysql_fetch_row($result);
}
echo json_encode($array);

Answer 1

log this value before sending,
var roll = document.getElementById("roll").value;
console.log(roll);
Use object to send the params in ajax call like this data: {'roll':roll} for best practice
use firebug to check if the value 'roll' passed properly
In your php dump the post variable print_r($_POST) and check the firebug response console whether you got what you sent.
If you got it in $_POST then probably you have some issue with sql connection/query