Спасибо .. мой ответ:
if ($result->num_rows > 0) {
# code...
$arr = [];
$inc = 0;
while ($row = $result->fetch_assoc()) {
# code...
$jsonArrayObject = (array('lat' => $row["lat"], 'lon' => $row["lon"], 'addr' => $row["address"]));
$arr[$inc] = $jsonArrayObject;
$inc++;
}
$json_array = json_encode($arr);
echo $json_array;
}
else{
echo "0 results";
}