How to use PHP to implement a simple online question and answer system-PHP Tutorial-php.cn

How to use PHP to implement a simple online question and answer system

Introduction:

With the development of the Internet, more and more people Begin to rely on the Internet for information and problem solving. Online Q&A and Q&A systems have become a very important tool for users to ask questions and get answers. In this article, we will learn how to use PHP language to implement a simple online question and answer system. Not only can you view and ask questions, but you can also answer them and communicate with other users.

Part One: Design the Database Structure

Before we begin, we need to design a database to store user, question and answer information. We can use MySQL as the database management system.

First, we create a database named "qa_system". Then we need to create three tables to store user, question, and answer information. The following is the design of these tables:

User table (users):

id: int (primary key)
username: varchar(50)
password: varchar(50)

Questions table (questions):

id: int (primary key)
user_id: int (foreign key , corresponding to the id field of the user table)
title: varchar(255)
content: text
created_at: datetime
updated_at: datetime

Answers table (answers):

id: int (primary key)
question_id: int (foreign key, corresponding to the id field of the question table)
user_id: int (foreign key, corresponding to the id field of the user table)
content: text
created_at: datetime
updated_at: datetime

Using the above table design, we can easily store information about users, questions and answers.

Part 2: Writing PHP Code

Create the homepage (index.php):

First, we will create a homepage that displays the latest List of questions and login/registration options.

<?php
// index.php

// 连接数据库
$conn = mysqli_connect("localhost", "username", "password", "qa_system");

// 查询最新的问题列表
$query = "SELECT * FROM questions ORDER BY created_at DESC";
$result = mysqli_query($conn, $query);

?>

<!DOCTYPE html>
<html>
<head>
    <title>在线问答系统</title>
</head>
<body>
    <h1>在线问答系统</h1>

    <h2>最新的问题：</h2>
    <?php while ($row = mysqli_fetch_assoc($result)) { ?>
        <h3><?php echo $row['title']; ?></h3>
        <p><?php echo $row['content']; ?></p>
    <?php } ?>

    <h2>登录/注册</h2>
    <form action="login.php" method="POST">
        <input type="text" name="username" placeholder="用户名">
        <input type="password" name="password" placeholder="密码">
        <input type="submit" value="登录">
    </form>
    
    <form action="register.php" method="POST">
        <input type="text" name="username" placeholder="用户名">
        <input type="password" name="password" placeholder="密码">
        <input type="submit" value="注册">
    </form>
</body>
</html>

Copy after login

Create the login page (login.php):

When the user fills in the username and password and clicks login, we will check whether the user exists in the database, if If exists, jump to the problem page.

<?php
// login.php

if ($_SERVER["REQUEST_METHOD"] == "POST") {
    // 获取用户提交的数据
    $username = $_POST["username"];
    $password = $_POST["password"];

    // 连接数据库
    $conn = mysqli_connect("localhost", "username", "password", "qa_system");

    // 查询用户信息
    $query = "SELECT * FROM users WHERE username = '$username' AND password = '$password'";
    $result = mysqli_query($conn, $query);

    // 检查用户是否存在
    if (mysqli_num_rows($result) > 0) {
        // 用户存在，将其用户信息存储到会话中并跳转到问题页面
        $user = mysqli_fetch_assoc($result);
        session_start();
        $_SESSION["user_id"] = $user["id"];
        header("Location: questions.php");
    } else {
        // 用户不存在，显示错误信息
        echo "用户名或密码错误";
    }
}
?>

<!DOCTYPE html>
<html>
<head>
    <title>用户登录</title>
</head>
<body>
    <h1>用户登录</h1>

    <form action="<?php echo htmlspecialchars($_SERVER["PHP_SELF"]); ?>" method="POST">
        <input type="text" name="username" placeholder="用户名">
        <input type="password" name="password" placeholder="密码">
        <input type="submit" value="登录">
    </form>
</body>
</html>

Copy after login

Create the registration page (register.php):

When the user fills in the user name and password and clicks registration, we will insert the new user into the database and jump Go to the questions page.

<?php
// register.php

if ($_SERVER["REQUEST_METHOD"] == "POST") {
    // 获取用户提交的数据
    $username = $_POST["username"];
    $password = $_POST["password"];

    // 连接数据库
    $conn = mysqli_connect("localhost", "username", "password", "qa_system");

    // 插入新用户
    $query = "INSERT INTO users (username, password) VALUES ('$username', '$password')";
    mysqli_query($conn, $query);

    // 跳转到问题页面
    header("Location: questions.php");
}
?>

<!DOCTYPE html>
<html>
<head>
    <title>用户注册</title>
</head>
<body>
    <h1>用户注册</h1>

    <form action="<?php echo htmlspecialchars($_SERVER["PHP_SELF"]); ?>" method="POST">
        <input type="text" name="username" placeholder="用户名">
        <input type="password" name="password" placeholder="密码">
        <input type="submit" value="注册">
    </form>
</body>
</html>

Copy after login

Create questions page (questions.php):

On this page we will display the details of a question and all the answers. Users can answer questions and communicate with other users.

<?php
// questions.php

// 连接数据库
$conn = mysqli_connect("localhost", "username", "password", "qa_system");

// 获取问题的ID
$question_id = $_GET["id"];

// 查询问题的详细信息
$query = "SELECT * FROM questions WHERE id = $question_id";
$question_result = mysqli_query($conn, $query);
$question = mysqli_fetch_assoc($question_result);

// 查询问题的回答列表
$query = "SELECT * FROM answers WHERE question_id = $question_id";
$answers_result = mysqli_query($conn, $query);

?>

<!DOCTYPE html>
<html>
<head>
    <title><?php echo $question["title"]; ?></title>
</head>
<body>
    <h1><?php echo $question["title"]; ?></h1>
    <p><?php echo $question["content"]; ?></p>

    <h2>回答：</h2>
    <?php while ($row = mysqli_fetch_assoc($answers_result)) { ?>
        <p><?php echo $row["content"]; ?></p>
    <?php } ?>

    <h2>我要回答：</h2>
    <?php
        session_start();
        $user_id = $_SESSION["user_id"];
    ?>
    <form action="answer.php" method="POST">
        <input type="hidden" name="question_id" value="<?php echo $question_id; ?>">
        <input type="hidden" name="user_id" value="<?php echo $user_id; ?>">
        <textarea name="content" rows="4" cols="50" placeholder="请输入您的答案"></textarea>
        <input type="submit" value="提交">
    </form>
</body>
</html>

Copy after login

Create the answer page (answer.php):

When the user fills in the answer and submits it, we will insert the answer into the database and refresh the question page.

<?php
// answer.php

if ($_SERVER["REQUEST_METHOD"] == "POST") {
    // 获取用户提交的数据
    $question_id = $_POST["question_id"];
    $user_id = $_POST["user_id"];
    $content = $_POST["content"];

    // 连接数据库
    $conn = mysqli_connect("localhost", "username", "password", "qa_system");

    // 插入新答案
    $query = "INSERT INTO answers (question_id, user_id, content) VALUES ($question_id, $user_id, '$content')";
    mysqli_query($conn, $query);

    // 跳转回问题页面
    header("Location: questions.php?id=$question_id");
}
?>

Copy after login

Summary:

Through the above steps, we successfully created a simple online Q&A and Q&A system. Users can register, log in and ask questions. Other users can view questions and answer them. This is just a basic implementation, you can add more features and user experience based on your needs. I hope this article can help you, and I wish you success in writing a PHP question and answer system!

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