SQL to CSV在php脚本中，组有多个'total‘行

<?php
// 连接到数据库
$servername = "数据库服务器地址";
$username = "数据库用户名";
$password = "数据库密码";
$dbname = "数据库名";

$conn = new mysqli($servername, $username, $password, $dbname);

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

// 执行SQL查询
$sql = "SELECT * FROM 表名";
$result = $conn->query($sql);

// 创建CSV文件并打开
$csvFile = fopen('output.csv', 'w');

// 写入CSV文件头
$fields = $result->fetch_fields();
$columnNames = array();
foreach ($fields as $field) {
    $columnNames[] = $field->name;
}
fputcsv($csvFile, $columnNames);

// 写入查询结果
while ($row = $result->fetch_assoc()) {
    fputcsv($csvFile, $row);
}

// 关闭CSV文件
fclose($csvFile);

// 关闭数据库连接
$conn->close();
?>