How to use PHP to implement data import and export functions

<form method="post" enctype="multipart/form-data" action="import.php">
    <input type="file" name="file" required>
    <input type="submit" value="导入">
</form>

$uploadPath = './uploads/';  // 上传文件保存路径
$uploadedFile = $uploadPath . basename($_FILES['file']['name']);  // 拼接上传文件的路径

if (move_uploaded_file($_FILES['file']['tmp_name'], $uploadedFile)) {
    echo '文件上传成功';
} else {
    echo '文件上传失败';
}

$data = [];  // 存储解析后的数据，格式为数组

// 使用第三方类库 PHPExcel 解析 Excel 文件
require_once './PHPExcel/PHPExcel.php';
$excelReader = PHPExcel_IOFactory::createReaderForFile($uploadedFile);
$excelReader->setReadDataOnly(true);
$excelObj = $excelReader->load($uploadedFile);
$worksheet = $excelObj->getActiveSheet();
$highestRow = $worksheet->getHighestRow();
$highestColumn = $worksheet->getHighestColumn();

for ($row = 2; $row <= $highestRow; $row++) {
    $rowData = $worksheet->rangeToArray('A' . $row . ':' . $highestColumn . $row, null, true, false)[0];
    // 解析每一行的数据，存入数组
    $data[] = [
        'field1' => $rowData[0],
        'field2' => $rowData[1],
        // ...
    ];
}

// 将数据存入数据库
foreach ($data as $row) {
    // 执行插入数据库的操作，这里以 MySQL 数据库作为示例
    $sql = "INSERT INTO table_name (field1, field2) VALUES ('{$row['field1']}', '{$row['field2']}')";
    // ...
    // 执行 sql 语句
}

// 查询数据库，获取需要导出的数据，这里以 MySQL 数据库作为示例
$sql = "SELECT * FROM table_name";
$result = mysqli_query($conn, $sql);
$data = [];

while ($row = mysqli_fetch_assoc($result)) {
    // 将每一行的数据存入数组
    $data[] = $row;
}

// 使用第三方类库 PHPExcel 生成 Excel 文件
require_once './PHPExcel/PHPExcel.php';
$excelObj = new PHPExcel();
$excelObj->setActiveSheetIndex(0);
$excelObj->getActiveSheet()->setTitle('Sheet1');
$row = 1;

foreach ($data as $rowData) {
    // 将数据填充到每一行的单元格
    $col = 0;
    foreach ($rowData as $value) {
        $excelObj->getActiveSheet()->setCellValueByColumnAndRow($col, $row, $value);
        $col++;
    }
    $row++;
}

$excelWriter = PHPExcel_IOFactory::createWriter($excelObj, 'Excel5');
$exportFile = './exports/export.xls';  // 导出文件保存路径
$excelWriter->save($exportFile);