1. Sum inventory from a specific supplier
| Ingredient | Supplier | Unit | Qty | Expiry Date |
| Olive Oil | Mediterranean Co | L | 12 | 2027-01-15 |
| Garlic | Fresh Farms | kg | 5 | 2024-10-05 |
| Tomato Sauce | Red Kitchen | can | 24 | 2025-06-20 |
| Basil | Fresh Farms | bundle | 8 | 2024-09-25 |
| Mozzarella | Dairy Plus | kg | 3 | 2024-09-20 |
| Parmesan | Dairy Plus | kg | 2 | 2027-03-10 |
| Flour | Golden Grain | kg | 15 | 2025-12-01 |
| Salt | Golden Grain | kg | 1 | 2027-06-30 |
=DSUM(A1:E8,"Qty",A10:B11)Result: 13
The formula sums all Qty values where Supplier equals 'Fresh Farms'. Two rows match: Garlic contributes 5 units and Basil contributes 8 units, totaling 13 items from that supplier.