PHP HELP

<?php
$servername = "";
$username = "";
$password = "";
$dbname = "";

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

$sql = "SELECT * FROM temp ORDER BY id DESC LIMIT 1";
$result = $conn->query($sql);

if ($result->num_rows > 0) {
    // output data of each row
    while($row = $result->fetch_assoc()) {
        $watertemp = $row["WaterTempC"];
        $ambienttemp = $row["AmbientTempC"];
            $temperature = $row["PIBoxT"];
    }
} else {

}
$conn->close();

header("Content-type: text/json");
// The x value is the current JavaScript time, which is the Unix time multiplied
// by 1000.
$x = time() * 1000;
// The y value is a random number


// Create a PHP array and echo it as JSON
$ret = array("Time:" .$x, "Temp:" .$watertemp);
$ret2 = array("Time:" .$x, "Temp:" .$ambienttemp);
$ret3 = array("Time:" .$x, "Temp:" .$PIBoxT);
//echo "[ ";
//echo str_replace('"', '', json_encode($ret));
//echo ", ";
//echo str_replace('"', '', json_encode($ret2));
//echo "]";

//echo json_encode($ret);

echo $watertemp . "/";

echo $ambienttemp . "/";

echo $temperature . "/";

?>