What are the best practices for handling loops and data duplication when exporting data to a CSV file in PHP?

When exporting data to a CSV file in PHP, it is important to handle loops and data duplication properly to ensure that each record is correctly written to the file without any duplicates. One way to achieve this is by using an associative array to store the data and then looping through the array to write each record to the CSV file. Additionally, you can use the `fputcsv()` function to automatically handle formatting and escaping of data.

// Sample data to export to CSV
$data = [
    ['John Doe', 'john.doe@example.com'],
    ['Jane Smith', 'jane.smith@example.com'],
    ['John Doe', 'john.doe@example.com'], // Duplicate data
];

// Open a file handle for writing
$fp = fopen('export.csv', 'w');

// Loop through the data and write each record to the CSV file
foreach ($data as $row) {
    fputcsv($fp, $row);
}

// Close the file handle
fclose($fp);