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PHP implements the question voting function in the knowledge question and answer website.

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PHP implements the question voting function in the Q&A website

With the popularity of smartphones and the Internet, the Q&A website has become an important platform for people to obtain information and share knowledge. A common feature in these Q&A sites is question voting. Users can rate the importance and quality of questions by voting, thereby helping other users better screen and find valuable questions.

This article will introduce how to use PHP to implement a simple question voting function. We'll use a MySQL database to store question and poll data, and HTML and CSS to build the front-end pages.

First, we need to create a database to store question and voting data. Suppose our database is called "qavote" and contains two tables "questions" and "votes". Here is the definition of the table:

CREATE TABLE questions (
  id INT(11) AUTO_INCREMENT PRIMARY KEY,
  title VARCHAR(255) NOT NULL,
  content TEXT NOT NULL
);

CREATE TABLE votes (
  id INT(11) AUTO_INCREMENT PRIMARY KEY,
  question_id INT(11) NOT NULL,
  vote_count INT(11) NOT NULL DEFAULT 0,
  FOREIGN KEY (question_id) REFERENCES questions(id)
);

Next, we need to create a PHP page to handle the question voting. We can name this page "vote.php". Here is a code example from the vote.php page:

<?php
// 连接数据库
$conn = new mysqli("localhost", "username", "password", "qavote");

// 检查数据库连接是否成功
if ($conn->connect_error) {
    die("数据库连接失败: " . $conn->connect_error);
}

// 检查是否传入了 question_id 和 action 参数
if (isset($_GET["question_id"]) && isset($_GET["action"])) {
    $question_id = $_GET["question_id"];
    $action = $_GET["action"];

    // 根据 action 参数执行相应的操作
    if ($action == "upvote") {
        // 更新问题的投票数
        $sql = "UPDATE votes SET vote_count = vote_count + 1 WHERE question_id = " . $question_id;
        $conn->query($sql);
    } elseif ($action == "downvote") {
        // 更新问题的投票数
        $sql = "UPDATE votes SET vote_count = vote_count - 1 WHERE question_id = " . $question_id;
        $conn->query($sql);
    }
}

// 关闭数据库连接
$conn->close();
?>

In vote.php, we first connect to the database and then check whether the question_id and action parameters were passed in. Based on the value of the action parameter, we update the number of votes for the corresponding question. Finally, we close the database connection. Note that to simplify the example, we do not do input validation and security. In practical applications, these are necessary.

Finally, we need to create an HTML page that displays the questions and voting results. The following is a simple example:

<!DOCTYPE html>
<html>
<head>
  <title>问题投票</title>
  <style>
    .question {
      margin-bottom: 20px;
    }
  </style>
</head>
<body>
  <?php
    // 连接数据库
    $conn = new mysqli("localhost", "username", "password", "qavote");

    // 检查数据库连接是否成功
    if ($conn->connect_error) {
        die("数据库连接失败: " . $conn->connect_error);
    }

    // 查询问题和投票数
    $sql = "SELECT questions.id, questions.title, questions.content, votes.vote_count FROM questions
            LEFT JOIN votes ON questions.id = votes.question_id";
    $result = $conn->query($sql);

    // 循环输出问题和投票结果
    if ($result->num_rows > 0) {
        while ($row = $result->fetch_assoc()) {
            echo "<div class='question'>";
            echo "<h3>" . $row["title"] . "</h3>";
            echo "<p>" . $row["content"] . "</p>";
            echo "<p>投票数: " . $row["vote_count"] . "</p>";
            echo "<a href='vote.php?question_id=" . $row["id"] . "&action=upvote'>赞同</a>";
            echo "<a href='vote.php?question_id=" . $row["id"] . "&action=downvote'>反对</a>";
            echo "</div>";
        }
    } else {
        echo "暂无问题";
    }

    // 关闭数据库连接
    $conn->close();
  ?>
</body>
</html>

In the above HTML page, we first connect to the database, then query the number of questions and votes, and output the questions and voting results based on the query results. For each question, we provide "thumbs up" and "thumbs down" links that users can click to vote. In practical applications, we can control voting permissions based on the user's login status.

Summary:
In this article, we learned how to use PHP and MySQL to implement the question voting function in a knowledge Q&A website. We created a database to store the questions and poll data and wrote the corresponding PHP pages and HTML pages. Although this is just a simple example, it can provide a good starting point for you to build more complete and complex Q&A websites. Hope this article can be helpful to you!

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