php 实现投票系统

创建数据库表结构

设计一个简单的投票系统数据库表，包含投票主题和选项。以下为MySQL示例：

CREATE TABLE polls (
    id INT AUTO_INCREMENT PRIMARY KEY,
    title VARCHAR(255) NOT NULL,
    description TEXT,
    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
);

CREATE TABLE poll_options (
    id INT AUTO_INCREMENT PRIMARY KEY,
    poll_id INT,
    option_text VARCHAR(255) NOT NULL,
    vote_count INT DEFAULT 0,
    FOREIGN KEY (poll_id) REFERENCES polls(id)
);

CREATE TABLE poll_votes (
    id INT AUTO_INCREMENT PRIMARY KEY,
    poll_id INT,
    option_id INT,
    user_ip VARCHAR(45),
    voted_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
    FOREIGN KEY (poll_id) REFERENCES polls(id),
    FOREIGN KEY (option_id) REFERENCES poll_options(id)
);

连接数据库

使用PDO建立数据库连接：

$host = 'localhost';
$dbname = 'voting_system';
$username = 'root';
$password = '';

try {
    $pdo = new PDO("mysql:host=$host;dbname=$dbname", $username, $password);
    $pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
} catch (PDOException $e) {
    die("Connection failed: " . $e->getMessage());
}

创建投票功能

实现添加新投票的功能：

function createPoll($title, $description, $options) {
    global $pdo;

    $stmt = $pdo->prepare("INSERT INTO polls (title, description) VALUES (?, ?)");
    $stmt->execute([$title, $description]);
    $pollId = $pdo->lastInsertId();

    foreach ($options as $option) {
        $stmt = $pdo->prepare("INSERT INTO poll_options (poll_id, option_text) VALUES (?, ?)");
        $stmt->execute([$pollId, $option]);
    }

    return $pollId;
}

显示投票界面

获取并显示投票内容：

function displayPoll($pollId) {
    global $pdo;

    $pollStmt = $pdo->prepare("SELECT * FROM polls WHERE id = ?");
    $pollStmt->execute([$pollId]);
    $poll = $pollStmt->fetch();

    $optionsStmt = $pdo->prepare("SELECT * FROM poll_options WHERE poll_id = ?");
    $optionsStmt->execute([$pollId]);
    $options = $optionsStmt->fetchAll();

    echo "<h3>{$poll['title']}</h3>";
    echo "<p>{$poll['description']}</p>";
    echo "<form method='post' action='vote.php'>";
    echo "<input type='hidden' name='poll_id' value='{$poll['id']}'>";

    foreach ($options as $option) {
        echo "<div><input type='radio' name='option_id' value='{$option['id']}' id='option{$option['id']}'>";
        echo "<label for='option{$option['id']}'>{$option['option_text']}</label></div>";
    }

    echo "<button type='submit'>Vote</button>";
    echo "</form>";
}

处理投票逻辑

记录投票并防止重复投票：

function processVote($pollId, $optionId) {
    global $pdo;

    $userIp = $_SERVER['REMOTE_ADDR'];

    // 检查是否已投票
    $checkStmt = $pdo->prepare("SELECT * FROM poll_votes WHERE poll_id = ? AND user_ip = ?");
    $checkStmt->execute([$pollId, $userIp]);

    if ($checkStmt->rowCount() > 0) {
        return false; // 已投票
    }

    // 记录投票
    $voteStmt = $pdo->prepare("INSERT INTO poll_votes (poll_id, option_id, user_ip) VALUES (?, ?, ?)");
    $voteStmt->execute([$pollId, $optionId, $userIp]);

    // 更新选项计数
    $updateStmt = $pdo->prepare("UPDATE poll_options SET vote_count = vote_count + 1 WHERE id = ?");
    $updateStmt->execute([$optionId]);

    return true;
}

显示投票结果

展示投票统计结果：

function displayResults($pollId) {
    global $pdo;

    $optionsStmt = $pdo->prepare("
        SELECT po.*, 
               (po.vote_count / (SELECT SUM(vote_count) FROM poll_options WHERE poll_id = ?) * 100) as percentage
        FROM poll_options po
        WHERE poll_id = ?
        ORDER BY vote_count DESC
    ");
    $optionsStmt->execute([$pollId, $pollId]);
    $options = $optionsStmt->fetchAll();

    echo "<h3>Voting Results</h3>";
    foreach ($options as $option) {
        echo "<div>{$option['option_text']}: {$option['vote_count']} votes (".round($option['percentage'], 2)."%)</div>";
        echo "<div style='background:#eee; height:20px; width:".$option['percentage']."%;'></div>";
    }
}

安全防护措施

增强系统安全性：

// 防止SQL注入
所有数据库查询都应使用预处理语句

// 限制投票频率
function canUserVote($pollId) {
    global $pdo;
    $ip = $_SERVER['REMOTE_ADDR'];
    $stmt = $pdo->prepare("SELECT COUNT(*) FROM poll_votes WHERE poll_id = ? AND user_ip = ? AND voted_at > DATE_SUB(NOW(), INTERVAL 1 DAY)");
    $stmt->execute([$pollId, $ip]);
    return $stmt->fetchColumn() == 0;
}

// 验证输入数据
function validateInput($data) {
    $data = trim($data);
    $data = stripslashes($data);
    $data = htmlspecialchars($data);
    return $data;
}

完整示例流程

典型的使用流程：

// 创建新投票
$options = ['Option 1', 'Option 2', 'Option 3'];
$pollId = createPoll('Favorite Color', 'What is your favorite color?', $options);

// 显示投票
displayPoll($pollId);

// 处理投票
if ($_SERVER['REQUEST_METHOD'] === 'POST' && isset($_POST['poll_id'], $_POST['option_id'])) {
    $success = processVote($_POST['poll_id'], $_POST['option_id']);
    if ($success) {
        echo "Thank you for voting!";
    } else {
        echo "You have already voted in this poll.";
    }
}

// 显示结果
displayResults($pollId);

这个实现包含了基本的投票系统功能，可以根据需要进一步扩展，如添加用户认证、多选投票、截止日期等功能。