如何使用PHP开发员工考勤系统？

id INT(11) PRIMARY KEY AUTO_INCREMENT,
name VARCHAR(50) NOT NULL,
position VARCHAR(50) NOT NULL

id INT(11) PRIMARY KEY AUTO_INCREMENT,
employee_id INT(11) NOT NULL,
date DATE NOT NULL,
check_in TIME NOT NULL,
check_out TIME NOT NULL

$name = $_POST['name'];
$position = $_POST['position'];

$sql = "INSERT INTO employee (name, position) VALUES ('$name', '$position')";
mysqli_query($conn, $sql);

$employee_id = $_POST['employee_id'];
$name = $_POST['name'];
$position = $_POST['position'];

$sql = "UPDATE employee SET name='$name', position='$position' WHERE id='$employee_id'";
mysqli_query($conn, $sql);

$employee_id = $_POST['employee_id'];

$sql = "DELETE FROM employee WHERE id='$employee_id'";
mysqli_query($conn, $sql);

<title>员工信息管理</title>

<h2>员工信息管理</h2>

<!-- 添加员工表单 -->
<h3>添加员工</h3>
<form method="post" action="#">
    <input type="text" name="name" placeholder="姓名" required>
    <input type="text" name="position" placeholder="职位" required>
    <input type="submit" name="add_employee" value="添加员工">
</form>

<!-- 员工列表 -->
<h3>员工列表</h3>
<table>
    <tr>
        <th>ID</th>
        <th>姓名</th>
        <th>职位</th>
        <th>操作</th>
    </tr>
    <?php while($row = mysqli_fetch_assoc($result)): ?>
    <tr>
        <td><?php echo $row['id']; ?></td>
        <td><?php echo $row['name']; ?></td>
        <td><?php echo $row['position']; ?></td>
        <td>
            <form method="post" action="#">
                <input type="hidden" name="employee_id" value="<?php echo $row['id']; ?>">
                <input type="text" name="name" value="<?php echo $row['name']; ?>">
                <input type="text" name="position" value="<?php echo $row['position']; ?>">
                <input type="submit" name="edit_employee" value="编辑">
                <input type="submit" name="delete_employee" value="删除">
            </form>
        </td>
    </tr>
    <?php endwhile; ?>
</table>

$employee_id = $_POST['employee_id'];
$date = $_POST['date'];
$check_in = $_POST['check_in'];
$check_out = $_POST['check_out'];

$sql = "INSERT INTO attendance (employee_id, date, check_in, check_out) VALUES ('$employee_id', '$date', '$check_in', '$check_out')";
mysqli_query($conn, $sql);

<title>考勤记录管理</title>

<h2>考勤记录管理</h2>

<!-- 添加考勤记录表单 -->
<h3>添加考勤记录</h3>
<form method="post" action="#">
    <select name="employee_id">
        <?php
        $sql = "SELECT * FROM employee";
        $result = mysqli_query($conn, $sql);
        while($row = mysqli_fetch_assoc($result)){
            echo "<option value='".$row['id']."'>".$row['name']."</option>";
        }
        ?>
    </select>
    <input type="date" name="date" required>
    <input type="time" name="check_in" required>
    <input type="time" name="check_out" required>
    <input type="submit" name="add_attendance" value="添加考勤记录">
</form>

<!-- 考勤记录列表 -->
<h3>考勤记录列表</h3>
<table>
    <tr>
        <th>ID</th>
        <th>姓名</th>
        <th>日期</th>
        <th>上班时间</th>
        <th>下班时间</th>
    </tr>
    <?php while($row = mysqli_fetch_assoc($result)): ?>
    <tr>
        <td><?php echo $row['id']; ?></td>
        <td><?php echo $row['name']; ?></td>
        <td><?php echo $row['date']; ?></td>
        <td><?php echo $row['check_in']; ?></td>
        <td><?php echo $row['check_out']; ?></td>
    </tr>
    <?php endwhile; ?>
</table>