<?php
    $username ="x";
    $password ="x";
    $hostname = "x";
    $database_name = "x";

    $con = mysql_connect($hostname, $username, $password);
    $selected = mysql_select_db($database_name);
    $mod = isset($_POST['username']) ? $_POST['username'] : '';
    $result = mysql_query("SELECT * FROM mydb WHERE username='{$mod}'");

    $json_response = array();
    while ($row = mysql_fetch_array($result, MYSQLI_ASSOC)) {
        $row_array['username'] = $row['username'];
        $row_array['time'] = $row['time'];
        array_push($json_response, $row_array);
    }

    echo json_encode(array('x' => $json_response));
?>