Detail data di modal , clause is ambiguous

saya ingin memunculkan detail data di modal, scrip tabelnya ini

<tbody>
          <?php
            $servername = "localhost";
            $username = "root";
            $password = "";
            $dbname = "db_smp11";

            // Membuat Koneksi
            $koneksi = new mysqli($servername, $username, $password, $dbname);

            // Melakukan Cek Koneksi
            if ($koneksi->connect_error) {
                die("Koneksi Gagal : " . $koneksi->connect_error);
            }

            //Melakukan query
            $sql = "SELECT * FROM member where level='siswa'";
            $hasil = $koneksi->query($sql);
            $no = 1;
            if ($hasil->num_rows > 0) {
                foreach ($hasil as $row) { ?>
                  <tr>
                  <td><?php echo $no; ?></td>
                  <td><?php echo $row['nisnip']; ?></td>
                  <td><?php echo $row['nama']; ?></td>
                  <td><?php echo $row['kelas']; ?></td>
                  <?php echo "<td><a href='#myModal' class='btn btn-default btn-small' id='siswaId' data-toggle='modal' data-id=".$row['nisnip'].">Detail</a></td>"; ?>
                  </tr>
            <?php
            $no++;
            }
              } else {
            echo "0 results";
              } $koneksi->close();
            ?>


          </tbody>

script dibawah

 <script type="text/javascript">
    $(document).ready(function(){
        $('#myModal').on('show.bs.modal', function (e) {
            var rowid = $(e.relatedTarget).data('nisnip');
            //menggunakan fungsi ajax untuk pengambilan data
            $.ajax({
                type : 'post',
                url : 'DetailSiswa.php',
                data :  'rowid='+ rowid,
                success : function(data){
                $('.fetched-data').html(data);//menampilkan data ke dalam modal
                }
            });
         });
    });
  </script>

detail siswanya

if($_POST['rowid']) {
        $nisnip = $_POST['rowid'];
        // mengambil data berdasarkan id
              mysql_connect("localhost","root");
              mysql_select_db("db_smp11");
        $sql = mysql_query("SELECT * FROM member,nilai,matapelajaran WHERE nilai.idmatapelajaran= matapelajaran.idmatapelajaran
                and member.nisnip=nilai.nisnip and nisnip=$nisnip");
        if($sql=== FALSE) {
die(mysql_error());
}
        $row = mysql_fetch_array($sql)?>
            <table class="table">
                <tr>
                    <td>Kode Barang</td>
                    <td>:</td>
                    <td><?php echo $row['namamatapelajaran']; ?></td>
                </tr>
                <tr>
                    <td>Nama Barang</td>
                    <td>:</td>
                    <td><?php echo $row['kkm']; ?></td>
                </tr>
                <tr>
                    <td>Deskripsi Barang</td>
                    <td>:</td>
                    <td><?php echo $row['ratarata']; ?></td>
                </tr>
            </table>
        <?php

        }

tp masalahnya, kl data gamuncul drtadi, diperbaiki malah "Column 'nisnip' in where clause is ambiguous" mohon bantuannya