Data Modeling Problem
Draw an REA diagram with cardinalities and tables with primary keys, foreign keys, and non-key attributes for the following business:
Boston Bottle (BB) buys and sells a variety of glass and plastic bottles nationwide. The proprietor of the company assigns each glass and bottle to an inventory type and assigns a unique # for each type (a type can contain numerous glasses and bottles). An individual sale or purchase can consist of multiple types of inventory. Inventory types are not tracked until they are purchased and put in a warehouse. A warehouse can have many inventory types, but it doesn't have to have any. An inventory type can be found in more than one warehouse.
Customers are not assigned to any particular salesperson: anyone can service them (a relationship is not needed). However, vendors typically deal with one and only one buyer, unless the buyer quits or leaves the employment of BB, in which case the vendor works with a different buyer. Buyers do not have to work with any vendors, if they just started, but they can work with many vendors. Each sale or purchase involves just one BB employee: a salesperson or buyer, respectively. Sales and purchases are only for inventory. These two types of employees are tracked in separate database tables. Customers and vendors are added to the database without any transactions taking place (including being assigned to a buyer in the case of a vendor), however they can be involved in many transactions over time.
Each employee fills out one timecard each week, therefore each timecard belongs to one and only one employee. The timecard allows the employee to get a paycheck on the last day of the following week. A separate check is written for each timecard and is made out to only one employee (or vendor in the case of a purchase). Timecard #’s for each employee change from week to week. Employees get a timecard immediately when they are hired. The...
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