PHP を使用して従業員勤怠システムを開発するにはどうすればよいですか?

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>