data filtering

<?php
/*
USE test;

DROP TABLE IF EXISTS data;
CREATE TABLE IF NOT EXISTS data(
id INT AUTO_INCREMENT PRIMARY KEY,
nama VARCHAR(10),
alamat VARCHAR(10),
jurusan VARCHAR(20)
);

INSERT INTO data(nama,alamat,jurusan)
VALUES
('riris','gresik','matematika'),
('mala','surabaya','pertanian'),
('lily','sidoarjo','informatika'),
('dimas','lamongan','akuntansi'),
('hany','jepara','biologi');
*/

$dbhost='localhost';
$dbuser='root';
$dbpass='';
$dbname='test';
$db=new mysqli($dbhost,$dbuser,$dbpass,$dbname);
$sql="SELECT ".(isset($_POST['field'])?'id,'.implode(',',$_POST['field']):'*')
    ." FROM data"
    .(isset($_POST['id'])?" WHERE id IN(".implode(',',$_POST['id']).")":'');
$result=$db->query($sql);
if($result->num_rows>0){
  $no=0;
  $data=array();
  while ($row = $result->fetch_assoc())
    $data[]=$row;
}
?>
<!doctype html>
<html>
  <head>
    <title>Tampil Data</title>
  </head>
  <body>
    <h2>Data </h2>
    <form method='post'>
      <table border='1'>
        <caption>QUERY: "<?php echo $sql;?>"</caption>
        <thead>
          <tr>
            <th>pilih</td>
            <th>No</th>
            <?php echo (!isset($data[0]['nama']) )?"":"<th>Nama<input type='checkbox' name='field[]' value='nama'></th>"; ?>
            <?php echo (!isset($data[0]['alamat']))?"":"<th>Alamat<input type='checkbox' name='field[]' value='alamat'></th>"; ?>
            <?php echo (!isset($data[0]['jurusan']))?"":"<th>Jurusan<input type='checkbox' name='field[]' value='jurusan'></th>"; ?>
          </tr>
        </thead>
        <tbody>
          <?php
          if($result->num_rows>0){
            foreach($data as $row)
              echo "
              <tr>
                <td><input type='checkbox' name='id[]' value='{$row['id']}'></td>
                <td>".++$no."</td>
                ".(isset($row['nama'])?"<td>{$row['nama']}</td>":"")."
                ".(isset($row['alamat'])?"<td>{$row['alamat']}</td>":"")."
                ".(isset($row['jurusan'])?"<td>{$row['jurusan']}</td>":"")."
              </tr>
              ";
          }else{
            echo "<tr><td colspan='4'>Tidak ada data terpilih</td></tr>";
          }
          ?>
        </tbody>
      </table>
      <input type='submit' name='submit' value='lihat'>
    </form>
  </body>
</html>