checkout.php

<?php 
    session_start();
    include "connect.php";
    $cart=@$_SESSION['cart'];
    if(count($cart)>0){
        $lama_pinjam=5; //satuan hari
        $tgl_harus_kembali=date('Y-m-d',mktime(0,0,0,date('m'),(date('d')+$lama_pinjam),date('Y')));
        mysqli_query($conn,"insert into peminjaman (id_siswa, tanggal_peminjaman, tanggal_kembali) value ('".$_SESSION['id_siswa']."','".date('Y-m-d')."','".$tgl_harus_kembali."')");
         $id=mysqli_insert_id($conn);
        foreach ($cart as $key_produk => $val_produk) {
            mysqli_query($conn,"insert into detail_peminjaman (id_peminjaman, id_buku, qty) value ('".$id['id_peminjaman']."','".$val_produk['id_buku']."','".$val_produk['qty']."')");
        }
        unset($_SESSION['cart']);
        echo '<script>alert("Success to checkout");location.href="history.php"</script>';
    }
?>