What is the best way to generate a unique, sequential number format like xxx.88.xxx.00 for each product?

To generate a unique, sequential number format like xxx.88.xxx.00 for each product, you can use a combination of an auto-incrementing ID and sprintf function in PHP. You can store the auto-incrementing ID in your database and then use sprintf to format the number as needed.

// Assuming $product_id is the auto-incrementing ID for each product
// Generate the unique number format
$unique_number = sprintf("%03d.88.%03d.00", $product_id, $product_id);

// Output the unique number format
echo $unique_number;