Let’s assume that you already have a database setup with a table called “users” and you want to export users and their email addresses to a CSV file.

<?php

// Connect and query the database for the users
$conn = new PDO("mysql:host=localhost;dbname=mydatabase", 'myuser', 'mypassword');
$sql = "SELECT username, email FROM users ORDER BY username";
$results = $conn->query($sql);

// Pick a filename and destination directory for the file
// Remember that the folder where you want to write the file has to be writable
$filename = "/tmp/db_user_export_".time().".csv";

// Actually create the file
// The w+ parameter will wipe out and overwrite any existing file with the same name
$handle = fopen($filename, 'w+');

// Write the spreadsheet column titles / labels
fputcsv($handle, array('Username','Email'));

// Write all the user records to the spreadsheet
foreach($results as $row)
{
fputcsv($handle, array($row['username'], $row['email']));
}

// Finish writing the file
fclose($handle);

?>

Notes:

in order for this to work, the path where you create the file needs to be writable
the sample code uses PHP's PDO class to connect to the database
complete explanation of the sample code (http://dev.strategystar.net/2012/01/export-data-from-a-database-to-csv-excel-with-php/)