PHPは知識問答サイトにユーザーポイントシステム機能を実装しています。

CREATE TABLE `user` (
  `id` INT(11) NOT NULL AUTO_INCREMENT,
  `username` VARCHAR(50) NOT NULL,
  `email` VARCHAR(50) NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

CREATE TABLE `score` (
  `id` INT(11) NOT NULL AUTO_INCREMENT,
  `user_id` INT(11) NOT NULL,
  `score` INT(11) NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

<?php
$servername = "localhost";
$username = "root";
$password = "password";
$dbname = "qa";

$conn = new mysqli($servername, $username, $password, $dbname);

if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
}
?>

<?php
require_once 'db.php';
?>

<?php
require_once 'db.php';

if ($_SERVER["REQUEST_METHOD"] === "POST") {
    $username = $_POST["username"];
    $email = $_POST["email"];

    $sql = "INSERT INTO user (username, email) VALUES ('$username', '$email')";

    if ($conn->query($sql) === TRUE) {
        echo "User registration successful!";
    } else {
        echo "Error: " . $sql . "<br>" . $conn->error;
    }
}

$conn->close();
?>

<form action="register.php" method="POST">
    <input type="text" name="username" placeholder="Username" required />
    <input type="email" name="email" placeholder="Email" required />
    <button type="submit">Register</button>
</form>

$score = 100;

$sql = "INSERT INTO score (user_id, score) VALUES (LAST_INSERT_ID(), '$score')";

if ($conn->query($sql) === TRUE) {
    echo "Score added successfully!";
} else {
    echo "Error: " . $sql . "<br>" . $conn->error;
}

<?php
require_once 'db.php';

if ($_SERVER["REQUEST_METHOD"] === "POST") {
    $username = $_POST["username"];

    $sql = "SELECT * FROM user WHERE username = '$username'";
    $result = $conn->query($sql);

    if ($result->num_rows > 0) {
        $user = $result->fetch_assoc();
        session_start();
        $_SESSION["user_id"] = $user["user_id"];
        $_SESSION["username"] = $user["username"];

        header("Location: profile.php");
    } else {
        echo "User not found!";
    }
}

$conn->close();
?>

<form action="login.php" method="POST">
    <input type="text" name="username" placeholder="Username" required />
    <button type="submit">Login</button>
</form>

<?php
require_once 'db.php';

session_start();
$user_id = $_SESSION["user_id"];

$sql = "SELECT * FROM user WHERE user_id = $user_id";
$result = $conn->query($sql);

if ($result->num_rows > 0) {
    $user = $result->fetch_assoc();

    echo "Username: " . $user["username"] . "<br>";
    echo "Email: " . $user["email"] . "<br>";

    $sql_score = "SELECT * FROM score WHERE user_id = $user_id";
    $result_score = $conn->query($sql_score);

    if ($result_score->num_rows > 0) {
        $score = $result_score->fetch_assoc();
        echo "Score: " . $score["score"] . "<br>";
    }
}

$conn->close();
?>

<?php
session_start();
if (!isset($_SESSION["user_id"])) {
    header("Location: index.php");
    exit;
}

require_once 'db.php';
?>

<h1>User Profile</h1>
<a href="logout.php">Logout</a>

<?php require_once 'profile.php'; ?>