ER Diagram for purchase and inventory system?

An ER diagram for a purchase and inventory system typically includes entities such as Product, Supplier, Customer, Order, and Inventory. The Product entity would have attributes like ProductID, Name, and Price, while Supplier would include SupplierID, Name, and ContactInfo. Relationships would show that a Supplier can provide multiple Products, a Customer can place multiple Orders, and each Order can include multiple Products, affecting Inventory levels. The Inventory entity would track quantities of each Product available, linking back to the Product entity.