Downloading records as CSV file

What is .csv file

Example of CSV file

1,"John Deo",Four,75,female

2,"Max Ruin",Three,85,male

<?php
require "config.php"; // Connection string 
dataConnect(); // Connect to Database

header("Content-type: application/octet-stream");
header("Content-Disposition: attachment; filename="my-student-data.csv"");
$data = "";

$query = $dbo->prepare("select *  FROM student");
$query->execute();

for($i=0; $row = $query->fetch(PDO::FETCH_NUM); $i++){
$data.="$row[0],$row[1],$row[2],$row[3],$row[4]"."\n";
}

unset($dbo); 
unset($query);

echo $data;
?>