Exportando dados do banco de dados em php, e o formato do arquivo para exportação do excel deve ser como pasta de trabalho do windows 97-2003

$file = 'D:/path/to/website/dump.sql';

// The SELECT...INTO query is unable to overwrite if the
// file already exists, so delete it beforehand:
if (is_file($file))
    unlink($file);

$query = "
    SELECT id, title, created   -- The fields to export
    INTO OUTFILE '{$file}'      -- The file
    FIELDS TERMINATED BY ','    -- Delimiter
    OPTIONALLY ENCLOSED BY '\"' -- Quote if necessary
    LINES TERMINATED BY '\n'    -- End line with LF newline
    FROM tbl_employee           -- Table name
";

$db = new MySQLi('localhost', 'root', '', 'your_database');
$db->query($query);

// Show any errors...
if ($db->error) {
    var_dump($db->error);
}