Example mysql query in php

$query = "select temp_f, hour from datalog use index (water_sensor)

where serialnum = '000800aa498e' order by hour desc limit 50";

$result = mysqli_query($link, $query);

$data = array();

for ($x = 0; $x < mysqli_num_rows($result); $x++0)

{

$data[] = mysqli_fetch_assoc($result);

}