如何使用PHP实现一个简单的在线调课和请假系统

表名: students
字段: id, name, email, password

表名: courses
字段: id, name, room, teacher

表名: schedule
字段: id, student_id, course_id, date, time

表名: leave_requests
字段: id, student_id, course_id, date_from, date_to, reason, status

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

// 创建数据库连接
$conn = new mysqli($servername, $username, $password, $dbname);

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

<?php
session_start();

if($_SERVER["REQUEST_METHOD"] == "POST") {
    if(isset($_POST['login'])) {
        $email = $_POST['email'];
        $password = $_POST['password'];

        // 查询数据库判断学生登录信息是否正确
        $sql = "SELECT id, name FROM students WHERE email = '$email' AND password = '$password'";
        $result = $conn->query($sql);

        if($result->num_rows == 1) {
            $row = $result->fetch_assoc();
            $_SESSION['id'] = $row['id'];
            $_SESSION['name'] = $row['name'];
            header("location: dashboard.php");
        } else {
            $error = "用户名或密码错误";
        }
    } elseif(isset($_POST['register'])) {
        $name = $_POST['name'];
        $email = $_POST['email'];
        $password = $_POST['password'];

        // 插入学生注册信息到数据库
        $sql = "INSERT INTO students (name, email, password) VALUES ('$name', '$email', '$password')";
        if($conn->query($sql) === TRUE){
            $success = "注册成功，请登录";
        }else{
            $error = "注册失败";
        }
    }
}
?>

<form method="POST" action="">
    <h2>学生登录</h2>
    <input type="email" name="email" placeholder="请输入邮箱" required>
    <input type="password" name="password" placeholder="请输入密码" required>
    <button type="submit" name="login">登录</button>

    <h2>学生注册</h2>
    <input type="text" name="name" placeholder="请输入姓名" required>
    <input type="email" name="email" placeholder="请输入邮箱" required>
    <input type="password" name="password" placeholder="请输入密码" required>
    <button type="submit" name="register">注册</button>
</form>

<?php
session_start();

// 检查学生是否登录
if(!isset($_SESSION['id'])) {
    header("location: login.php");
    exit;
}

if($_SERVER["REQUEST_METHOD"] == "POST") {
    if(isset($_POST['change_course'])) {
        $course_id = $_POST['course_id'];
        $date = $_POST['date'];

        // 更新学生课程信息到数据库
        $sql = "UPDATE schedule SET course_id = '$course_id' WHERE student_id = ".$_SESSION['id']." AND date = '$date'";
        if($conn->query($sql) === TRUE){
            $success = "调课成功";
        }else{
            $error = "调课失败";
        }
    } elseif(isset($_POST['leave_request'])) {
        $course_id = $_POST['course_id'];
        $date_from = $_POST['date_from'];
        $date_to = $_POST['date_to'];
        $reason = $_POST['reason'];

        // 插入请假信息到数据库
        $sql = "INSERT INTO leave_requests (student_id, course_id, date_from, date_to, reason, status) VALUES (".$_SESSION['id'].", $course_id, '$date_from', '$date_to', '$reason', 'pending')";
        if($conn->query($sql) === TRUE){
            $success = "请假申请已提交";
        }else{
            $error = "请假申请失败";
        }
    }
}
?>

<form method="POST" action="">
    <h2>调课</h2>
    <select name="course_id">
        <?php
        // 查询学生课程信息
        $sql = "SELECT id, name FROM courses";
        $result = $conn->query($sql);
        while($row = $result->fetch_assoc()) {
            echo "<option value='".$row['id']."'>".$row['name']."</option>";
        }
        ?>
    </select>
    <input type="date" name="date" required>
    <button type="submit" name="change_course">确认调课</button>

    <h2>请假</h2>
    <select name="course_id">
        <?php
        // 查询学生课程信息
        $sql = "SELECT id, name FROM courses";
        $result = $conn->query($sql);
        while($row = $result->fetch_assoc()) {
            echo "<option value='".$row['id']."'>".$row['name']."</option>";
        }
        ?>
    </select>
    <input type="date" name="date_from" required>
    <input type="date" name="date_to" required>
    <textarea name="reason" placeholder="请输入请假原因" required></textarea>
    <button type="submit" name="leave_request">提交请假</button>
</form>