Instructions:

$-$ Identify any entities needed to deal with Many$-$to$-$Many $($M:M$)$ relationships or ternary or n$-$ary relationships. But be sure to check your relationships for the correct cardinalities.

$-$ Identify primary and foreign keys needed in your model.

$-$ Show cardinalities and relationship names on all relationship lines. Use two cardinality symbols at both ends of each relationship line.

Dental Supply Inventory:

Your organization is a medium sized single$-$site community dental clinic, and you will model the operations of the Supply Department $($SD$).$ The SD orders, stocks, and distributes consumable supplies to other operating departments $($OD$)$ of the clinic. Supplies are ordered from vendors, some of which are manufacturers. While each vendor tends to specialize in certain categories of supplies there are no hard and fast rules and some supplies are provided by more than one vendor.

Most orders to vendors are for multiple items and always for case$-$lot sized units of each item and items are priced by the case. Prices change from order to order.

Receipt of supplies is recorded, and a delivery may include some or all of the items on a vendor order and may even include items from more than one order to the same vendor. If any items are received the entire quantity of that item ordered will have been shipped.

The SD receives requests for supplies from OD and satisfies them with daily 'retail' distributions of items.

All items in stock will be delivered and back ordered items will be distributed when available.

OD order some items as individual items $($e$.$g$.,$ dental surgical loupes$)$ while some are ordered as box or bag lots $($e$.$g$.,$ latex gloves$).$

The Supply Department maintains a current charge back price for items according to the unit of issue and adjusts these prices as vendor prices change. The SD maintains a storeroom with aisles, racks, and shelves $($aisles have racks and racks have shelves$)$ and each supply item has a storage location. Some oversized items have numbered floor storage locations that do not belong to an aisle, rack, or shelf.