mysqli_multi_query

<?php
    $koneksi = mysqli_connect('localhost','root','','db_belajar');
    if (mysqli_connect_errno()) {
        echo "koneksi gagal ".mysqli_connect_error();
        exit();
    }
    /*
    anggaplah kita memiliki sebuah database bernama db_belajar
    serta 3 buah tabel bernama 'tb_user','buku' dan sekolah.
    */
    $query = "SELECT nama,username FROM tb_user ;";
    $query .= "SELECT judul,penerbit FROM buku ;";
    $query .= "SELECT nama,kelas FROM sekolah ";
    $data  = mysqli_multi_query($koneksi, $query)or die(mysqli_error($koneksi));
    do {
        $simpan = mysqli_store_result($koneksi, $data);
        while ($row = mysqli_fetch_row($simpan)) {
            echo $row[0]."<br/>";
            echo $row[1]."<br/>";
        }
        mysqli_free_result($simpan);
        if (mysqli_more_results($koneksi)) {
            echo "<br/>";
        }
    } while (mysqli_next_result($koneksi));
?>