Sort the results byseries_idso all products with the same value will be together.

$stmt = $pdo->prepare("SELECT series_id, product_name FROM yourTable ORDER BY series_id"); $stmt->execute();

Then, when displaying the results, display the series title and start a new one if it changes

$last_series = null; echo "
\n"; while ($row = $stmt->fetch(PDO::FETCH_ASSOC)) { if ($row['series_id'] != $last_series) { if ($last_series) { echo "
\n"; } echo "
" . $row['series_id'] . " Series Product\n"; echo "
\n"; $last_series = $row['series_id']; } echo "
" . $row['product_name'] . "
\n"; } if ($last_series) { echo "\n"; } echo "
\n";