How to: Ajax check values in php/database - php

Question

How to POST values from submit and check if they exist in mysql?
And what do I have to type in my .php file?
document.addEventListener("deviceready", onDeviceReady, false);
function onDeviceReady() {
$('#login').submit(function(){
var username = document.getElementById("username").value;
var password = document.getElementById("password").value;
});
}
function getData(sendData) {
$.ajax({
type: 'POST',
url: 'http://www.url.php',
data: { 'username': username, 'password': password },
success: afhandeling,
});
}

Answer 1

Call ajax like this:
jQuery.ajax({
type: "POST",
url: "http://www.url.php",
data: { username:username,password:password },
success: function( data )
{
}
});
and in ajax file:
if (isset($_POST['username']) && isset($_Post['password']))
{
$query = "SELECT * FROM users WHERE username='".$_POST['username']."' AND password=".$_POST['password'];
$result = mysql_query($query);
$row = mysql_fetch_assoc($result);
if($row)
{
echo 'login';
}
else
{
echo "error";
}
}

Answer 2

I think the URL has to be a local one, i.e. "/projects/blindchat/login.php".
On that page you can write something like this:
if (isset($_POST['username']) && isset($_POST['password'])) {
// MYSQL query:
SELECT 1 FROM users WHERE username = ? AND password = ?
}
Remember you have to escape the variables first to prevent SQL injection.

Answer 3

In login.php page you need to do something like this:
if(isset($_POST['username']) && isset($_Post['password'])) {
$q = "SELECT * FROM users WHERE username=$_POST['username'] AND password=$_POST['password']"
$r = mysql_query($q);
if(mysql_num_rows($r)==1) //Do Login
else echo "ERROR";
}

Answer 4

You submit the form which launches your ajax script that sends the data over to your PHP file that handles the input and gives you an answer.
Use PDO or MySqLi. Mysql is depreceated and no longer supported. My example below uses the PDO method.
Your PHP should look something like this(this is untested code, so there might be typos):
<?php
$username = $_POST['username'];
$password = $_POST['password'];
if (!empty($username) && !empty($password)) {
// We create a PDO connection to our database
$con = new PDO("mysql:host=yourhost;dbname=yourdatabase", "username", "password");
// We prepare our query, this effectively prevents sql injection
$query = $con->prepare("SELECT * FROM table WHERE username=:username AND password=:password LIMIT 1");
// We bind our $_POST values to the placeholders in our query
$query->bindValue(":username", $username, PDO::PARAM_STR);
$query->bindValue(":password", $password, PDO::PARAM_STR);
// We execute our query
$query->execute();
$result = $query->fetch(); // Grab the matches our query produced
// Here we check if we found a match in our DB
if (!empty($result)) {
echo "Matches were found";
} else {
echo "No matches found";
}
} else {
echo "Please fill out all fields";
}
?>
As for getting a reply from your AJAX script you can simply alert the response or show it as you please.
success: function(data) {
alert(data);
}