Wednesday, February 6, 2019

Scenario to ERD


 A Bus Company owns a number of busses. Each bus is allocated to a particular route, although some routes may have several busses. Each route passes through a number of towns. One or more drivers are allocated to each stage of a route, which corresponds to a journey through some or all of the towns on a route. Some of the towns have a garage where busses are kept and each of the busses are identified by the registration number and can carry different numbers of passengers, since the vehicles vary in size and can be single or double-decked. Each route is identified by a route number and information is available on the average number of passengers carried per day for each route. Drivers have an employee number, name, address, and sometimes a telephone number.



Scenario to ERD


Suppose you are given the following requirements for a simple database for the National
Hockey League (NHL):
  • · the NHL has many teams,
  • · each team has a name, a city, a coach, a captain, and a set of players,
  • · each player belongs to only one team,
  • · each player has a name, a position (such as left wing or goalie), a skill level, and a set
  • of injury records,
  • · a team captain is also a player,
  • · a game is played between two teams (referred to as host_team and guest_team) and has a date (such as May 11th, 1999) and a score (such as 4 to 2).


Construct a clean and concise ER diagram for the NHL database using the Chen notation
as in your textbook. List your assumptions and clearly indicate the cardinality mappings
as well as any role indicators in your ER diagram.




Scenario to ERD


A bus company wants to keep track of its bus routes and schedules. Design an ER diagram for the database according to the following description. Identify all constraints and keys: Each bus route has a route number, a departure station and a destination station. For each bus route, there is a schedule, which records the departure times of buses. For each departure time of each route, a driver and a bus can be assigned (however this is not necessary - information about the driver or the bus may sometimes be missing). A driver has an employee Id, a name and a phone number. A bus is identified by its license number. The database also records the seating capacity of each bus.



Scenario to ERD



UPS prides itself on having up-to-date information on the processing and current location of each shipped item. To do this, UPS relies on a company-wide information system. Shipped items are the heart of the UPS product tracking information system. Shipped items can be characterized by item number (unique), weight, dimensions, insurance amount, destination, and final delivery date. Shipped items are received into the UPS system at a single retail center. Retail centers are characterized by their type, uniqueID, and address. Shipped items make their way to their destination via one or more standard UPS transportation events (i.e., flights, truck deliveries). These transportation events are characterized by a unique scheduleNumber, a type (e.g, flight, truck), and a eliveryRoute.

Please create an Entity Relationship diagram that captures this information about the UPS
system. Be certain to indicate identifiers and cardinality constraints.







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