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php选课实现

2026-02-28 14:45:31PHP

PHP 选课系统实现

数据库设计

创建数据库表存储学生、课程和选课记录。学生表（students）包含学号、姓名等字段；课程表（courses）包含课程ID、名称、容量等；选课表（enrollments）关联学生和课程。

CREATE TABLE students (
    student_id INT PRIMARY KEY,
    name VARCHAR(100)
);

CREATE TABLE courses (
    course_id INT PRIMARY KEY,
    name VARCHAR(100),
    capacity INT
);

CREATE TABLE enrollments (
    enrollment_id INT PRIMARY KEY AUTO_INCREMENT,
    student_id INT,
    course_id INT,
    FOREIGN KEY (student_id) REFERENCES students(student_id),
    FOREIGN KEY (course_id) REFERENCES courses(course_id)
);

连接数据库

使用PDO连接MySQL数据库，确保在PHP中配置正确的数据库凭据。

$dsn = 'mysql:host=localhost;dbname=course_selection';
$username = 'username';
$password = 'password';

try {
    $pdo = new PDO($dsn, $username, $password);
} catch (PDOException $e) {
    echo 'Connection failed: ' . $e->getMessage();
}

选课功能实现

处理学生选课请求，检查课程容量是否已满，避免重复选课。

if ($_SERVER['REQUEST_METHOD'] === 'POST' && isset($_POST['enroll'])) {
    $studentId = $_POST['student_id'];
    $courseId = $_POST['course_id'];

    // 检查课程容量
    $stmt = $pdo->prepare("SELECT COUNT(*) FROM enrollments WHERE course_id = ?");
    $stmt->execute([$courseId]);
    $enrolledCount = $stmt->fetchColumn();

    $stmt = $pdo->prepare("SELECT capacity FROM courses WHERE course_id = ?");
    $stmt->execute([$courseId]);
    $capacity = $stmt->fetchColumn();

    if ($enrolledCount >= $capacity) {
        echo "课程已满";
    } else {
        // 检查是否已选
        $stmt = $pdo->prepare("SELECT * FROM enrollments WHERE student_id = ? AND course_id = ?");
        $stmt->execute([$studentId, $courseId]);
        if ($stmt->fetch()) {
            echo "已选该课程";
        } else {
            // 插入选课记录
            $stmt = $pdo->prepare("INSERT INTO enrollments (student_id, course_id) VALUES (?, ?)");
            $stmt->execute([$studentId, $courseId]);
            echo "选课成功";
        }
    }
}

显示可选课程

从数据库查询并显示所有可选课程，包括当前选课人数和剩余容量。

$stmt = $pdo->query("
    SELECT c.course_id, c.name, c.capacity, COUNT(e.enrollment_id) as enrolled 
    FROM courses c 
    LEFT JOIN enrollments e ON c.course_id = e.course_id 
    GROUP BY c.course_id
");

while ($row = $stmt->fetch()) {
    echo "课程: {$row['name']}, 容量: {$row['capacity']}, 已选: {$row['enrolled']}";
}

安全性考虑

使用预处理语句防止SQL注入，对用户输入进行验证和过滤。

$studentId = filter_input(INPUT_POST, 'student_id', FILTER_VALIDATE_INT);
$courseId = filter_input(INPUT_POST, 'course_id', FILTER_VALIDATE_INT);

if (!$studentId || !$courseId) {
    die("无效输入");
}

用户界面

创建简单的HTML表单供学生选择课程，显示选课结果和错误信息。

php选课实现

<form method="post">
    <input type="hidden" name="student_id" value="123">
    <select name="course_id">
        <?php foreach ($courses as $course): ?>
            <option value="<?= $course['course_id'] ?>"><?= $course['name'] ?></option>
        <?php endforeach; ?>
    </select>
    <button type="submit" name="enroll">选课</button>
</form>

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