DATABASE MODELING FOR HOTE DU AUSTRIA: PROBLEM & SOLN.

Transcription

1 DATABASE MODELING FOR HOTE DU AUSTRIA: PROBLEM & SOLN. PROBLEM Assume that you are an employee of a consultancy firm. Your firm has been hired to design and implement a database to support operations at the Hote Austria. A description of the hotel follows: du The hotel has three branches with all branches located in the same city. Each branch of the hotel has 100 rooms - (10 suites, 50 single rooms, 40 double rooms). Each branch of the hotel houses and manages a 4-star restaurant named Michelin, an entertainment lounge, a bar, a physical fitness room, a travel agency, a drugstore and a swimming pool for the guests. The travel agency which is named Travel City provides travel services for making local and international travel arrangements for guests and walk-ins. Customers visiting the travel services go to different branches of the hotel on different days depending on their convenience. The drugstore is named Trustworthy and is open 24 hours a day, 7 days a week. It provides service to both guests and walk-ins. Lately, Trustworthy s managers have noticed that many customers go to more than one branch to fill their prescriptions. Since some customers have allergies or relevant medical conditions, it would be best for the managers of different branches to share the information on the customer s medical history. Each manager, however, wishes to have total control over data about their branch operations. Currently, the customers use cash or credit card as a payment method, every time they encounter an expense at the hotel. One of the policies of the management is to provide fast, convenient and unobtrusive service to customers such that a guest need not carry money to enjoy the hotel s amenities. In order to facilitate this policy, the management desires to include billing of meal, travel, drugstore, and entertainment expenses to the guest s room-bill as and when the expenses are incurred. The management also desires to support instantaneous querying facility (on-line input with real time processing) of room bill status by management and authorized members of the staff. The new system should include a menu screen that can be used by the hotel receptionists to answer queries from guests. 1

2 IDENTIFY ENTITY CLASSES (MARKED WITH OUTLINE) Assume that you are an employee of a consultancy firm. Your firm has been hired to design and implement a database to support operations at the Hote Austria. A description of the hotel follows: du The hotel has three branches with all branches located in the same city. Each branch of the hotel has 100 rooms - (10 suites, 50 single rooms, 40 double rooms). Each branch of the hotel houses and manages a 4-star restaurant named Michelin, an entertainment lounge, a bar, a physical fitness room, a travel agency, a drugstore and a swimming pool for the guests. The travel agency which is named Travel City provides travel services for making local and international travel arrangements for guests and walk-ins. Customers visiting the travel services go to different branches of the hotel on different days depending on their convenience. The drugstore is named Trustworthy and is open 24 hours a day, 7 days a week. It provides service to both guests and walk-ins. Lately, Trustworthy s managers have noticed that many customers go to more than one branch to fill their prescriptions. Since some customers have allergies or relevant medical conditions, it would be best for the managers of different branches to share the information on the customer s medical history. Currently, the customers use cash or credit card as a payment method, every time they encounter an expense at the hotel. One of the policies of the management is to provide fast, convenient and unobtrusive service to customers such that a guest need not carry money to enjoy the hotel s amenities. In order to facilitate this policy, the management desires to include billing of meal, travel, drugstore, and entertainment expenses to the guest s room-bill as and when the expenses are incurred. The management also desires to support instantaneous querying facility (on-line input with real time processing) of room bill status by management and authorized members of the staff. The new system should include a menu screen that can be used by the hotel receptionists to answer queries from guests. Comment [WIU1]: We will assume city is not relevant or will be treated as an attribute. Comment [WIU2]: Subtypes of rooms. Comment [WIU3]: Facilities! Comment [WIU4]: Information about relationships. Comment [WIU5]: An entity! Comment [WIU6]: Information about relationships. Comment [WIU7]: We will ignore this for this problem. Comment [WIU8]: Subtypes. Comment [WIU9]: Expense types. Comment [WIU10]: It doesn t look like we need to store this data skip as an Eclass. 2

3 LIST ECLASSES AND ATTRIBUTES Branch: location Room: Suites Single Double Facility: Lounge Bar Fitness Travel Drugstore Pool Guest: Resident (we gave this a name) Walk-in Payment method: Cash Credit card Expense: Room Meal Travel Drugstore Entertainment Room bill: Comment [WIU11]: subtypes Comment [WIU12]: subtypes Comment [WIU13]: subtypes but we will not maintain this distinction. Comment [WIU14]: subtypes Comment [WIU15]: room added as an expense subtype. Meal, Travel.. are other subtypes. NOTE THAT THERE ARE PRACTICALLY NO ATTRIBUTES; OTHERWISE THEY ARE GENERALLY LISTED TO THE RIGHT OF THE ECLASSES. 3

4 MAP/VERBALIZE RELATIONSHIPS Branch has rooms. Guests occupy rooms at branches. (three way relationship between guests, rooms and branches). Branch has facilities (note no relationships between rooms and facilities). Guests use facilities at branches and incur expenses. Guest pay for expenses using payment method (note relationship between guests, facilities, expenses and payment method) this is a four way relationship. Expenses appear on the room bill for resident guests. (note that we have some flexibility in the way we treat guests and expenses we will not distinguish walk-ins from residents since both have to pay expenses) DRAW AN ER DIAGRAM Study the ER diagram below and note the following: Since there is only one attribute, attributes are not being shown here. Note the use of max cardinality in 3 way and four way relationships. Note that cardinalities are not shown in the case of class/sub-class relationships. We are not differentiating between residents and walk-ins. Note the use of a blank box to denote extra sub types not shown. There are two cycles present, but unavoidable because guest is involved in multiple relationships. Rooms should be connected to the relationship between method, expenses and guests this is not shown for clarity and will result in another cycle. 4

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