$conn = new mysqli($servername, $username, $password, $dbname);
// Check connection
if ($conn->connect_error) {
  die("Connection failed: " . $conn->connect_error);
}

echo "LISTA ORIGIAL<br>";
$sql_David_original = "SELECT * FROM Ttabela";
$result_David = $conn -> query($sql_David_original);
while($row0 = $result_David -> fetch_assoc()) {
      echo $row0["ID"] . "<br>";
}

echo "<br>LISTA NOVA<br>";
$num_rows = $result_David -> num_rows;
for($i = 0; $i < $num_rows; $i++) {
       echo $i . "<br>";
}