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php实现和MySQL实现评论

2026-02-15 03:32:55PHP

PHP 实现评论功能

使用 PHP 和 MySQL 实现评论功能需要创建数据库表、编写 PHP 脚本处理表单提交，以及显示评论内容。

创建 MySQL 表存储评论数据：

CREATE TABLE comments (
    id INT AUTO_INCREMENT PRIMARY KEY,
    name VARCHAR(100) NOT NULL,
    email VARCHAR(100),
    comment TEXT NOT NULL,
    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
);

创建评论表单 HTML：

<form action="post_comment.php" method="post">
    <input type="text" name="name" placeholder="Your Name" required>
    <input type="email" name="email" placeholder="Your Email">
    <textarea name="comment" placeholder="Your Comment" required></textarea>
    <button type="submit">Submit Comment</button>
</form>

处理表单提交的 PHP 脚本 (post_comment.php)：

<?php
$conn = new mysqli('localhost', 'username', 'password', 'database');

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

$name = $conn->real_escape_string($_POST['name']);
$email = $conn->real_escape_string($_POST['email']);
$comment = $conn->real_escape_string($_POST['comment']);

$sql = "INSERT INTO comments (name, email, comment) VALUES ('$name', '$email', '$comment')";

if ($conn->query($sql) === TRUE) {
    header("Location: comments.php");
} else {
    echo "Error: " . $sql . "<br>" . $conn->error;
}

$conn->close();
?>

显示评论的 PHP 脚本 (comments.php)：

<?php
$conn = new mysqli('localhost', 'username', 'password', 'database');

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

$sql = "SELECT * FROM comments ORDER BY created_at DESC";
$result = $conn->query($sql);

if ($result->num_rows > 0) {
    while($row = $result->fetch_assoc()) {
        echo "<div class='comment'>";
        echo "<h3>" . htmlspecialchars($row['name']) . "</h3>";
        echo "<p>" . htmlspecialchars($row['comment']) . "</p>";
        echo "<small>" . $row['created_at'] . "</small>";
        echo "</div>";
    }
} else {
    echo "No comments yet.";
}

$conn->close();
?>

MySQL 实现评论功能

在 MySQL 中创建评论系统主要涉及表设计和查询优化。

创建带有外键关系的评论表：

CREATE TABLE users (
    user_id INT AUTO_INCREMENT PRIMARY KEY,
    username VARCHAR(50) NOT NULL UNIQUE,
    email VARCHAR(100) NOT NULL UNIQUE
);

CREATE TABLE posts (
    post_id INT AUTO_INCREMENT PRIMARY KEY,
    title VARCHAR(255) NOT NULL,
    content TEXT NOT NULL,
    user_id INT,
    FOREIGN KEY (user_id) REFERENCES users(user_id)
);

CREATE TABLE comments (
    comment_id INT AUTO_INCREMENT PRIMARY KEY,
    content TEXT NOT NULL,
    user_id INT,
    post_id INT,
    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
    FOREIGN KEY (user_id) REFERENCES users(user_id),
    FOREIGN KEY (post_id) REFERENCES posts(post_id)
);

查询特定文章的所有评论：

SELECT c.content, u.username, c.created_at
FROM comments c
JOIN users u ON c.user_id = u.user_id
WHERE c.post_id = 1
ORDER BY c.created_at DESC;

计算每篇文章的评论数量：

SELECT p.title, COUNT(c.comment_id) as comment_count
FROM posts p
LEFT JOIN comments c ON p.post_id = c.post_id
GROUP BY p.post_id;

实现嵌套评论系统：

CREATE TABLE nested_comments (
    comment_id INT AUTO_INCREMENT PRIMARY KEY,
    content TEXT NOT NULL,
    user_id INT,
    post_id INT,
    parent_id INT NULL,
    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
    FOREIGN KEY (user_id) REFERENCES users(user_id),
    FOREIGN KEY (post_id) REFERENCES posts(post_id),
    FOREIGN KEY (parent_id) REFERENCES nested_comments(comment_id)
);

查询嵌套评论及其回复：

WITH RECURSIVE comment_tree AS (
    SELECT comment_id, content, user_id, parent_id, 0 AS depth
    FROM nested_comments
    WHERE parent_id IS NULL AND post_id = 1

    UNION ALL

    SELECT nc.comment_id, nc.content, nc.user_id, nc.parent_id, ct.depth + 1
    FROM nested_comments nc
    JOIN comment_tree ct ON nc.parent_id = ct.comment_id
)
SELECT * FROM comment_tree ORDER BY depth, created_at;

php实现和MySQL实现评论