--getData.php--
<?php
$servername = "localhost";
$username = "root";
$password = "";
$dbname = "tugas";
// Create connection
$conn = mysqli_connect($servername, $username, $password, $dbname);
$query = mysqli_query($conn,"SELECT * FROM tb_barang AS A LEFT JOIN tb_category AS B ON A.category=B.id");
$rows = array();
while($r = mysqli_fetch_assoc($query)) {
    $rows[] = $r;
}
print json_encode($rows);

--updateData.php--
<?php
$servername = "localhost";
$username = "root";
$password = "";
$dbname = "tugas";
$id = $_GET['id'];
$nama = $_GET['nama'];
$harga = $_GET['harga'];
// Create connection
$conn = mysqli_connect($servername, $username, $password, $dbname);
$query="UPDATE tb_barang SET nama = '$nama',harga='$harga' WHERE id='$id'";
if($query = mysqli_query($conn,$query)){
    echo("{\"sukses\":true}");
}else{
    echo("{\"sukses\":false}");
}

--deleteData.php--
<?php
$servername = "localhost";
$username = "root";
$password = "";
$dbname = "tugas";
$id = $_GET['id'];
// Create connection
$conn = mysqli_connect($servername, $username, $password, $dbname);
$query="DELETE FROM tb_barang where id='$id'";
if($query = mysqli_query($conn,$query)){
    echo("{\"sukses\":true}");
}else{
    echo("{\"sukses\":false}");
}

--login.php--
<?php
if(!empty($_GET['username']) and !empty($_GET['password']) ){
    $servername = "localhost";
    $username = "root";
    $password = "";
    $dbname = "tugas";
    $user = $_GET['username'];
    $pass = $_GET['password'];
    // Create connection
    $conn = mysqli_connect($servername, $username, $password, $dbname);
    $query = mysqli_query($conn,"SELECT * FROM `tb_user` WHERE username = '$user' AND username = '$pass'");
    if(mysqli_num_rows($query)>0){
        echo("{\"sukses\":true}");
    }else{
        echo("{\"sukses\":false}");
    }
}