php android login

//index.php
<?php

if (isset($_POST['tag']) && $_POST['tag'] != '') {
    $tag = $_POST['tag'];
    require_once 'include/DB_Functions.php';
    $db = new DB_Functions();
    $response = array("tag" => $tag, "error" => FALSE);
    if ($tag == 'login') {
        $email = $_POST['email'];
        $password = $_POST['password'];

        $user = $db->getUserByEmailAndPassword($email, $password);
        if ($user != false) {
            $response["error"] = FALSE;
            $response["uid"] = $user["unique_id"];
            $response["user"]["name"] = $user["name"];
            $response["user"]["email"] = $user["email"];
            $response["user"]["created_at"] = $user["created_at"];
            $response["user"]["updated_at"] = $user["updated_at"];
            echo json_encode($response);
        } else {
            $response["error"] = TRUE;
            $response["error_msg"] = "Incorrect email or password!";
            echo json_encode($response);
        }
    } else if ($tag == 'register') {
        $name = $_POST['name'];
        $email = $_POST['email'];
        $password = $_POST['password'];

        if ($db->isUserExisted($email)) {
           $response["error"] = TRUE;
            $response["error_msg"] = "User already existed";
            echo json_encode($response);
        } else {
            $user = $db->storeUser($name, $email, $password);
            if ($user) {
                $response["error"] = FALSE;
                $response["uid"] = $user["unique_id"];
                $response["user"]["name"] = $user["name"];
                $response["user"]["email"] = $user["email"];
                $response["user"]["created_at"] = $user["created_at"];
                $response["user"]["updated_at"] = $user["updated_at"];
                echo json_encode($response);
            } else {
                $response["error"] = TRUE;
                $response["error_msg"] = "Error occured in Registartion";
                echo json_encode($response);
            }
        }
    } else {
        $response["error"] = TRUE;
        $response["error_msg"] = "Unknow 'tag' value. It should be either 'login' or 'register'";
        echo json_encode($response);
    }
} else {
    $response["error"] = TRUE;
    $response["error_msg"] = "Required parameter 'tag' is missing!";
    echo json_encode($response);
}
?>


2) Config.php
<?php
define("DB_HOST", "localhost");
define("DB_USER", "root");
define("DB_PASSWORD", "toor");
define("DB_DATABASE", "android_api");
?>

3)DB_Connect.php
<?php
class DB_Connect {
    function __construct() {
    }
function __destruct() {
    }
    public function connect() {
        require_once 'include/Config.php';
        $con = mysql_connect(DB_HOST, DB_USER, DB_PASSWORD) or die(mysql_error());
        mysql_select_db(DB_DATABASE) or die(mysql_error());

        return $con;
    }
    public function close() {
        mysql_close();
    }
}
?>

4)DB_Functions.php
<?php

class DB_Functions {

    private $db;

    function __construct() {
        require_once 'DB_Connect.php';
        $this->db = new DB_Connect();
        $this->db->connect();
    }

    function __destruct() {

    }

    public function storeUser($name, $email, $password) {
        $uuid = uniqid('', true);
        $hash = $this->hashSSHA($password);
        $encrypted_password = $hash["encrypted"];
        $salt = $hash["salt"];
        $result = mysql_query("INSERT INTO users(unique_id, name, email, encrypted_password, salt, created_at) VALUES('$uuid', '$name', '$email', '$encrypted_password', '$salt', NOW())");
        if ($result) {
            $uid = mysql_insert_id();
            $result = mysql_query("SELECT * FROM users WHERE uid = $uid");
            return mysql_fetch_array($result);
        } else {
            return false;
        }
    }

    public function getUserByEmailAndPassword($email, $password) {
        $result = mysql_query("SELECT * FROM users WHERE email = '$email'") or die(mysql_error());
        $no_of_rows = mysql_num_rows($result);
        if ($no_of_rows > 0) {
            $result = mysql_fetch_array($result);
            $salt = $result['salt'];
            $encrypted_password = $result['encrypted_password'];
            $hash = $this->checkhashSSHA($salt, $password);
            if ($encrypted_password == $hash) {
                return $result;
            }
        } else {
            return false;
        }
    }
    public function isUserExisted($email) {
        $result = mysql_query("SELECT email from users WHERE email = '$email'");
        $no_of_rows = mysql_num_rows($result);
        if ($no_of_rows > 0) {
            return true;
        } else {
            return false;
        }
    }
    public function hashSSHA($password) {
        $salt = sha1(rand());
        $salt = substr($salt, 0, 10);
        $encrypted = base64_encode(sha1($password . $salt, true) . $salt);
        $hash = array("salt" => $salt, "encrypted" => $encrypted);
        return $hash;
    }
    public function checkhashSSHA($salt, $password) {
        $hash = base64_encode(sha1($password . $salt, true) . $salt);
        return $hash;
    }
}
?>