Worked on the Huuquoc99/DATN_107 repository to enhance inventory management and order processing by implementing inventory stock deduction upon order placement. Developed a centralized function to manage product variant quantities, ensuring that stock levels in the database accurately reflect completed orders for both authenticated and guest users. The approach focused on backend development using PHP and database management techniques, with all changes traceable to a specific commit for transparency. This work improved the reliability of order fulfillment by aligning inventory data with real-time transactions, addressing the need for accurate stock tracking and supporting robust order processing workflows within the application.