eror nya kenapa ya

<?php

$koneksi = mysqli_connect("localhost", "root", "", "db_kampus");

$inner_join = mysqli_query('SELECT mahasiswa.nim, mahasiswa.nama, mahasiswa.kode_jurusan, jurusan.nama_jurusan, jurusan.kode_jurusan FROM mahasiswa INNER JOIN jurusan ON mahasiswa.kode_jurusan=jurusan.kode_jurusan');

echo "Inner Join Tabel<br>";

echo "<table border='1'>";

echo "<tr><td>NIM</td>

<td>Nama</td>

<td>Jurusan</td>

</tr>";

while ($join=mysqli_fetch_array($inner_join)){

echo "<tr>

<td>$join[0]</td>

<td>$join[1]</td>

<td>$join[2]</td>

<td>$join[3]</td>

<td>$join[4]</td>

</tr>";

}

echo "</table>";

?>