Concept explainers
A cellular operator needs a
Can a customer have an unlimited number of plans?- Can a customer exist without a plan?
- Is it possible to create a plan without knowing who the customer is?
- Does the operator want to limit the types of handsets that can be linked to a specific plan type?
- Is it possible to maintain data regarding a handset without connecting it to a plan?
- Can a handset be associated with multiple plans?
- Assume a handset type exists that can utilize multiple operating systems. Could this situation be accommodated within the model included in Figure 2-24?
- Is the company able to track a manufacturer without maintaining information about its handsets?
- Can the same
operating system be used on multiple handset types? - There are two relationships between Customer and Plan. Explain how they differ.
- Characterize the degree and the cardinalities of the relationship that connects Customer to itself. Explain its meaning.
- Is it possible to link a handset to a specific customer in a plan with multiple customers?
- Can the company track a handset without identifying its operating system?
Want to see the full answer?
Check out a sample textbook solutionChapter 2 Solutions
Modern Database Management (12th Edition)
Additional Engineering Textbook Solutions
Starting Out With Visual Basic (8th Edition)
C How to Program (8th Edition)
Programming in C
Starting Out with Java: From Control Structures through Objects (7th Edition) (What's New in Computer Science)
Java How to Program, Early Objects (11th Edition) (Deitel: How to Program)
C++ How to Program (10th Edition)
- Design ER diagram to model the online bookstore’s database, in which there are four entities, namely books, authors, publishers, and customers entities. Every book has an author and a publisher. Customers can order books. Information about payment, shipping, and stock of goods does not need to be included in the model.arrow_forwardDraw an entity relationship diagram ERD using unified modelling language UML nation according to the below business rules. your design should be logical level-including primary and foreign key fields and remember to remove any many-to-many relationships. 1. all entities should have surrogate primary keys. 2.A customer can place many orders over and over time and each order is placed by exactly one customer. 3.The name and surname of a customer must be stored in the database 4.The date and status of an order must be stored in the database 5.Each order cab obtain many items and each item can be part of many different orders 6.The name description and unit price of every item must be stored in the database 7.When an item is added to an order, the quality ordered and the unit price of thr item must be stored 8.Each item in the database belongs to a catagory and a catagory has many items that belong to it 9.The name of each of the categories must be stored in the databasearrow_forwardDraw the ER diagram based on the following specification. A tutorial school is using a database to manage information about teachers, courses, and students. Each teacher is identified by staff_id, has a name, an email address, and a phone number. Each student is identified by student_id, has a name, an email address, and a registration date. Each course is identified by course_id, year, and semester. In addition, each course has a name. Each course is associated with multiple lessons. A lesson has a lesson number, a location, a date, a start-time, and an end-time. Lesson numbers are sequentially numbers, starting from 1, generated separately for each course. Each teacher teaches at least one course. Each student takes at least one course. Each course is taught by one teacher. Each course can be taken by many students.arrow_forward
- Consider the E-R diagram for a university database as shown in Figure 1. What does deparment represent?(a) An entity(b) An attribute set(c) An entity set(d) A relationship setarrow_forwardDATABASE SYSTEM DRAWING E/R DIAGRAM AND RELATIONAL SCHEMA.Draw the ERD with appropriate mapping cardinalities for mail order database in which employees, each identified by unique employee number, first name last name and ZIP code. Employee are categorized as manager, clerk ad delivery staff. Each customer of the company is identified by a unique employee number, first and last name and ZIP code. Each part sold by the company is identified by unique part number, part name, price and quantity stock. Each order placed by a customer is taken by a clerk and is given a unique order number. Each order contains specified quantities of one or more parts. Each order has a date of receipt as well as an expected ship date. The actual ship date is also recorded. The delivery boy places the order of specified customers. There is a provision of replacing one or many fault parts to the customer but before that it must be verified by the manager.arrow_forwardDesign an E-R diagram for a database for an airlines system. The database must keep track of customers and their reservations, flights and their status, seat assignments on individual flights and the schedule and routing of future flights. Apply all the database design constraints as much as possible.arrow_forward
- Please read this carefully and Draw an EER diagram for a database of a hospital following these requirements: create Four to five regular strong entities. A union One 1:1, one 1:N, and one N:M relationship – of which at least one relationship should be partial and one full. One overlap relationship and one disjoint relationship. Other notes: Do not emphasize on too many attributes for the entities. Two to three attributes for each entity will be enough. Make sure to include a primary key for each entity.arrow_forwardUse Lucidchart to draw an ERR Diagram with this information: EER Diagram for Royal Victoria Hospital Information System Assumptions: The diagram focuses on the entities and relationships. Attributes with cardinality are assumed to be single-valued. Dates are assumed as identifiers for visits. Entities: Person: (person_ID, name, address, birth_date, phone_number) Employee: (inherits from Person, date_hired) Nurse: (inherits from Employee, certificate) Staff: (inherits from Employee, job_class) Technician: (inherits from Employee, skill) Physician: (inherits from Person, speciality, pager_number) Patient: (inherits from Person, contact_date, resident_flag) Outpatient: (inherits from Patient) Resident: (inherits from Patient) Visit: (date, comments, outpatient_ID) Care Centre: (name, location) Laboratory: (name, location) Bed: (bed_number, room_number, care_centre_ID) Item: (item_number, description, unit_cost) Treatment:…arrow_forwardDesign ER Diagram for a hotel reservation database, your ER Diagram should include the following: * Hotel * Hotel Branch * Room * Customer * Employee * Supplier: supplies beds, bed sheets, pillows, ... etc * Customers can reserve rooms Think of attributes and relationships that you need to have in your ER Diagram. • Your ER diagram should include entities, attributes, relationship and cardinality constraints.arrow_forward
- What are the rules for choosing how to recognize and create connections between entities in the ER-Model?arrow_forwardWhat is the purpose of entity-relationship diagrams? What sort of symbol is used to depict a connection, and how does it work? What exactly does the phrase "associative entity" imply and what does it mean? Give an example.arrow_forwardDraw an Entity Relationship Diagram (ERD) using Unified Modelling Language (UML) notation according to the following business rule for a hotel group: a. Each hotel is located in a city. Some cities may have more than one hotel, but a specific hotel can only be located in one city. The name of the hotel and the name of the city must be stored in the databasearrow_forward
- Principles of Information Systems (MindTap Course...Computer ScienceISBN:9781285867168Author:Ralph Stair, George ReynoldsPublisher:Cengage LearningFundamentals of Information SystemsComputer ScienceISBN:9781305082168Author:Ralph Stair, George ReynoldsPublisher:Cengage Learning