无法通过mysqli_connect存储数据

大家好，我目前正在尝试为android应用程序创建登录活动，但我不知道为什么注册时未存储用户数据。php文件是否有问题，如下所示？

Register.php为用户存储注册

<?php
    $con = mysqli_connect("mysql13.000webhost.com", "a1641537_fetch", "password", "a1641537_fetchdb");

    $name = $_POST["name"];
    $username = $_POST["username"];
    $password = $_POST["password"];

    $statement = mysqli_prepare($con, "INSERT INTO Fetch (name, username, password) VALUES (?, ?, ?) ");

    mysqli_stmt_bind_param($statement, "sss", $name, $username, $password);
    mysqli_stmt_execute($statement);

    mysqli_stmt_close($statement);

    mysqli_close($con);
?>

FetchUserData.php获取用户的用户名和密码。

<?php
    $con = mysqli_connect("mysql13.000webhost.com", "a1641537_fetch", "password", "a1641537_fetchdb");

    $username = $_POST["username"];
    $password = $_POST["password"];

    $statement = mysqli_prepare($con, "SELECT * FROM Fetch WHERE username = ? AND password = ?");
    mysqli_stmt_bind_param($statement, "ss", $username, $password);
    mysqli_stmt_execute($statement);

    mysqli_stmt_store_result($statement);
    mysqli_stmt_bind_result($statement, $name, $username, $password);

    $user = array();

    while(mysqli_stmt_fetch($statement)) {
        $user[name] = $name;
        $user[username] = $username;
        $user[password] = $password;
    }

    echo json_encode($user);

    mysqli_stmt_close($statement);

    mysqli_close($con);
?>