A store in Thohoyandou decides to go High Tech. You are asked to design a database for the store. After brainstorming wi

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A store in Thohoyandou decides to go High Tech. You are asked to design a database for the store. After brainstorming with the store managers, you come up with the following specification:

•The store has multiple departments, identified by their names.

•Each dept may have many employees but (at most) one of them is the dept

manager.

•Employees are identified by their names. We also need to record their salaries. Each employee works in exactly one department. Managers are employees as well, each with a salary higher than all other employees in the department he manages.

•The store sells various items identified by item ID’s. Exactly one

department carries each item, while each department may carry many

items. For each item, we also need to keep a short description and its

quantity in stock.

•The store deals with a number of suppliers identified by their names. We

need to record their addresses.

•Each supplier supplies an item at a particular price. A supplier may supply

any number of items, and each item must be supplied by at least 3 suppliers (probably different prices).

•The store receives orders identified by order ID’s. Each order has a date, a

shipping address, and may include different quantities of multiple items.

(a) Draw an ER diagram for the database identifying:

i) all entities

ii) all relationships

iii) the primary key for each entity (including weak entities) and each relationship;

(b) Convert the ER design into a relationship scheme. For each relation state:

i) the name of the relation

ii) the names of attributes

iii)

the primary key

iv) the foreign key