Premium Essay

Er Models and Diagrams

In: Computers and Technology

Submitted By Rameshbabu
Words 811
Pages 4
Publisher
Ms. Contract would like you to design a conceptual schema for her agency using the entity-relationship model. She represents authors and publishing companies and helps them draw up contracts. The business rules include: * Each book is described by a unique ISBN, year of publication, sales price, and number of pages. * Each author is described by a unique name and phone number. * Each book is written by at least one authors. Because there can possibly be multiple authors for a book, this relationship is described by an attribute role; values are primary-author, editor, etc. * Ms. Contract maintains author information even if they have not authored any book as yet. * Each publishing company is identified by a unique name and phone number. * Each book must be under-review by at least one publishing company, and this relationship is described by an expiration date. * There are several editors who work for each publisher, and each publisher has at least one editor. However, editors are not independent of publishers. * Therefore, each editor is identified by a combination of a unique name and the publisher name, and a phone number. * For each book that is finally completed and published by a publisher, there is a single author who signs-a-contract for that book. There is an attribute date associated with each contract. Note that this is a ternary relationship.

Answers: 1. ER Schema:
Entities, Attributes and Primary Keys
Book (ISBN, pubYear, price, pages)
Author (aName, phoneNo)
Publisher (pName, phoneNo)
Editor (eName, phoneNo)

Relationships, Degrees and Participating Entities
WrittenBy: binary relationship (role)
1 Book to 1 or more Author
1 Author to 0 or more Books
UnderReview: binary relationship (expDate, -month, -day, -year)
1 Book to 1 or more Publisher
1 Publisher to 0 or more Books
WorksFor:...

Similar Documents

Free Essay

An Experimental Comparison of Er and Uml Class Diagrams for Data Modelling

...Empir Software Eng (2010) 15:455–492 DOI 10.1007/s10664-009-9127-7 An experimental comparison of ER and UML class diagrams for data modelling Andrea De Lucia · Carmine Gravino · Rocco Oliveto · Genoveffa Tortora Published online: 11 December 2009 © Springer Science+Business Media, LLC 2009 Editor: Erik Arisholm Abstract We present the results of three sets of controlled experiments aimed at analysing whether UML class diagrams are more comprehensible than ER diagrams during data models maintenance. In particular, we considered the support given by the two notations in the comprehension and interpretation of data models, comprehension of the change to perform to meet a change request, and detection of defects contained in a data model. The experiments involved university students with different levels of ability and experience. The results demonstrate that using UML class diagrams subjects achieved better comprehension levels. With regard to the support given by the two notations during maintenance activities the results demonstrate that the two notations give the same support, while in general UML class diagrams provide a better support with respect to ER diagrams during verification activities. Keywords Controlled experiments · Entity-relation diagrams · UML class diagrams · Design notations · Comprehension · Maintenance · Verification The work described in this paper is supported by the project METAMORPHOS (MEthods and Tools for migrAting software systeMs towards...

Words: 16567 - Pages: 67

Premium Essay

Object-Relational Database Modeling Using Uml

...Introduction……………………………………………………………………………………..4 Overview of ER Modeling and UML…………………………………………………………...4 UML Meta-model……………………………………………………………………………… 6 UML Components………………………………………………………………………………7 UML Data Profile……………………………………………………………………………….9 UML Diagrams……………………………………………………………………………….....10 UML Diagram Classification – Static, Dynamic, and Implementation…....................................12 4+1 View of UML Diagrams……………………………………………………………………13 Object-oriented Class Model and Relational Database Model..............................................…...14 Use of UML to develop Ontologies…………………………………………………………..…17 References……………………………………………………………………………………….19 Abstract The Unified Modeling Language (UML) is being used as the de-facto standard in the software industry. With the adoption of UML 2.0, the new enhancements allow this version to describe many of the elements found in today's software technology as well as Model Driven Architecture and Service-Oriented Architecture. Many existing software applications involve complex application layer implemented in object-oriented programming languages and at the same time use relational database systems as the back-end data store. Modeling the whole system in a consistent manner will help developers and end users better understand the application. The Unified Modeling Language (UML) is a standard language for modeling software and database systems. Data model of object-relational databases (ORDBs) is a great......

Words: 3708 - Pages: 15

Premium Essay

Database Management

...CIV E 603: Information Modeling and Database Systems Lecture 1 1 What to Study?  Introduction to Data base  Relational Model  Database design  Structured Query Language (SQL) 22 Let’s begin the journey !! …. in to fascinating world of databases 23 Today’s outline  Database Management System (DBMS)  Entity-Relationship (ER) Model 24 What is a database?  Many people would like to call it organization… 25 What is a database? Database is a structured collection of related data. Many name it efficiency… 26 A database is  A home for data – since that is where data stay…  A manager for data – since data are organized neatly…  A GOOGLE for data – since a particular record can be found in a snap…  A guardian for data – since a database rejects malicious accesses…  … 27 What is a Database? Database: is a collection of related data Data: known facts that can be recorded and that have implicit meaning Properties of database: • represents some aspect of the real world (mini-world -UoD) • logically coherent collection of data with some inherent meaning. A random assortment of data cannot correctly be referred to as a database. • designed, built, and populated with data for a specific purpose. It has an intended groups of users. 28 What is a Database? A database can be of any size and of varying complexity. • For example, the list......

Words: 2400 - Pages: 10

Premium Essay

Data Modeling

...2. The Entity-Relationship Model 2. The Entity-Relationship Model This section’s goal: After completing this chapter, you should be able to explain the three phases of database design, Why are multiple phases useful? evaluate the significance of the Entity-Relationship Model (ER model) for DB design, enumerate the basic constructs of the ER model, develop ER diagrams (schemas in the ER model) for a given application, translate ER models into equivalent (as far as possible) relational models. Marc H. Scholl (DBIS, Uni KN) Information Management Winter 2007/08 48 2. The Entity-Relationship Model Introduction Database design (1) Overall goal of DBMS usage: Efficiently develop programs to support given real-world tasks. These programs need to store data persistently. To develop these programs, apply proven methods of software engineering—specialized to support data-intensive programs. Definition (Database Design) Database Design is the process of developing a database schema for a given application. DB design is a subtask of the overall software engineering effort. Marc H. Scholl (DBIS, Uni KN) Information Management Winter 2007/08 49 2. The Entity-Relationship Model Introduction Database design (2) The specification of programs and data is intertwined: The schema should contain the data needed by the programs. Programs are often easy to develop once the structure of the data to be manipulated has been specified. Data, however, is an......

Words: 7024 - Pages: 29

Premium Essay

Good

...CS446/646 E-R Model The Entity-Relationship (ER) Model Lecture Topics Basic ER modelling         Extensions to ER modelling Designing an ER schema Reducing ER diagrams to relational schema 1 CS446/646 E-R Model Overview of ER Model Proposed by Peter Chen in 1976 Used for database (conceptual schema) design World/enterprise described in terms of entities       attributes relationships Visualization: ER-diagram 2 CS446/646 E-R Model Basic ER Modelling Entity: a distinguishable object Entity set: set of entities of same type Ex. students currently at the Institute       flights offered by Air Canada burglaries in Ontario during 1994 Graphical representation of entity sets: Student Flight Burglary 3 CS446/646 E-R Model Basic ER Modelling (cont’d) Attributes describe poperties of entities Domain: set of permitted values for an attribute Graphical representation of attributes Student Major StudentNum StudentName     ¢¡  Ex. for Employee-entities: EmpNum, Name, Salary, 4 CS446/646 E-R Model Basic ER Modelling (cont’d) Relationship: representation of the fact that certain entities are related to each other Relationship set: set of relationships of a given type Ex. students registered in courses         passengers booked on flights parents and their children bank branches, customers and their accounts In order for a relationship to exist, the participating......

Words: 1337 - Pages: 6

Free Essay

Data Base Esign

...entity. The Pet Store can have many pets, but the pets can’t belong to many stores. * An example of a many-to-many is brand names-to-cookies. There are many brand names and there are many types of cookies. A brand can make many types of cookies and a cookie type can be made by many different brands. 3. What is an attribute? * An attribute is a property or characteristic of an entity. Three entities and their attributes are (A) gun (make, model), (B) airline (name, model), and (C) A camera (make, type). Part Two 3. What column or columns should be selected as the primary key to best meet the desired properties for a primary key in exhibit 2-17? * I chose the column labeled student id as having the best properties for being a primary key. I also chose student id because there is a zero probability of that number being issued to, or duplicated by another student. All of the other candidate keys could either be replicated or shared. 4. In the ER diagram in Exhibit 2-18 identify the foreign key. * In the ER diagram in Exhibit 2-18, I...

Words: 483 - Pages: 2

Free Essay

Documentation Techniques

...------------------------------------------------- Documentation Techniques Five documentation techniques include data flow diagrams, entity relationship diagrams, system flowcharts, program flowcharts, and record layout diagrams. Data Flow Diagrams and Entity Relationship Diagrams * Data flow diagrams – Data flow diagrams (DFD) use symbols to represent the entities, processes, data flows, and data stores that pertain to a system. * Entities – Entities in a DFD are objects that lie at the boundary of the system being modeled. They are the sources of and destinations for data and can be other interfacing systems or entities external to the organization. Entities are labeled as singular nouns on a DFD. Data stores represent the accounting files and records used in each process, and the labeled arrows represent data flows between processes, data stores, and entities. * Processes – Processes are labeled with a descriptive verb. Process objects should not be represented as nouns. The arrows connecting objects should be labeled to represent specific flows of data. Also, each data flow label should be unique. The same label should not be attached to two different flow lines in the same DFD. * Usage – Systems analysts use DFDs extensively to represent the logical elements of the system. It does not depict the physical system. * Entity relationship diagrams – An entity relationship diagram is used to represent the relationship between business......

Words: 735 - Pages: 3

Premium Essay

Database Management

...databases? Briefly discuss each. 1.3. Discuss the main characteristics of the database approach and how it differs from traditional file systems. 1.4. What are the responsibilities of the DBA and the database designers? 1.5. What are the different types of database end users? Discuss the main activities of each. 1.6. Discuss the capabilities that should be provided by a DBMS. 1.7. Discuss the differences between database systems and information retrieval systems. Chapter 2: Review Questions 2.1. Define the following terms: data model, database schema, database state, internal schema, conceptual schema, external schema, data independence, DDL, DML, SDL, VDL, query language, host language, data sublanguage, database utility, catalog, client/server architecture, three-tier architecture, and n-tier architecture. 2.2. Discuss the main categories of data models. What are the basic differences between the relational model, the object model, and the XML model? 2.3. What is the difference between a database schema and a database state? 2.4. Describe the three-schema architecture. Why do we need mappings between schema levels? How do different schema definition languages support this architecture? 2.5. What is the difference between logical data independence and physical data independence? Which one is harder to achieve? Why? 2.6. What is the difference between procedural and nonprocedural DMLs? 2.7. Discuss the different types of user-friendly interfaces and the types of users who......

Words: 1108 - Pages: 5

Premium Essay

Database Management System Case Study

...For example, the elements writer, novel, and consumer may be described using ER diagrams this way: ER diagram with basic objects In the diagram, the elements inside rectangles are called entities while the items inside diamonds denote the relationships between entities. ER Model is represented by means of an ER diagram. Any object, for example, entities, attributes of an entity, relationship sets, and attributes of relationship sets, can be represented with the help of an ER diagram. Entity Entities are represented by means of rectangles. Rectangles are named with the entity set they represent. Attributes Attributes are the properties of entities. Attributes are represented by means of ellipses. Every ellipse represents one attribute and is directly connected to its entity (rectangle). If the attributes are composite, they are further divided in a tree like structure. Every node is then connected to its attribute. That is, composite attributes are represented by ellipses that are connected with...

Words: 1326 - Pages: 6

Premium Essay

Benefits of Relational Models

...of Relational Models to ACME Global Consulting Geoff Roberts Professor Rahat Zafar Intro to Relational Database Management Systems 1/16/13 Businesses thrive on information. To succeed, you must have the most current knowledge to stay competitive in a rapidly changing industry, such as Information Technology. The trick is, not only knowing where to find the information, but how and where to secure it. Databases are the keystones to any business looking for organization and quality management. They will allow your company to track expenses, market trends, employees, equipment, and most importantly, clients. The question? How do I deploy an efficient database? In order to implement a database, it should be planned out to ensure it meets all requirements of the organization. Consider your own company’s needs for a moment. Organizational charts, certifications, client accounts, investments. How are these examples mapped so that the information is readily accessible in an efficient way? The answer, employ Relational Models from which a functional database that meets all level requirements can derive from. This is a major step in becoming a prepared, well organized, and respected consulting firm. A Relational model or entity-relationship diagram (ERD) is a data modeling technique that creates a graphical representation of the entities, and the relationships between entities, within an information system (http://searchcrm.techtarget.com). Relational models help to......

Words: 624 - Pages: 3

Premium Essay

Patient and Service Management

...MANAGEMENT 1-2 1.3 NEED OF DATABASE IN PATIENT AND SERVICE MANAGEMENT SYSTEM 2 1.4 SCOPE 2 2) ADVANCED AND EXISTING SYSTEM ( 3) 2.1 LIMITATIONS OF EXISTING SYSTEM 3 3) ER DIARAM RELATIONSHIPS IN APTIENT AND SERVICE MANAGEMENT SYSTEM (3-4) 3.1 INTRODUCTION TO E-R MODELS 3-4 3.2 E-R DIAGRAM OF PATIENT AND SERVICE MANAGEMENT SYSTEM...

Words: 1361 - Pages: 6

Premium Essay

Data Modeling

...cr. (4,50 ECTS cr.) Teaching methods (Full-time, daytime studies): Lectures - 16 h per semestre Laboratory works - 32 h per semestre Individual work - 72 h per semester Course aim Understandig of models and system of information resourses. Jelena Mamčenko Introduction to Data Modeling and MSAccess CONTENT 1 Introduction to Data Modeling ............................................................................................................... 5 1.1 Data Modeling Overview ............................................................................................................... 5 1.1.1 Methodology .......................................................................................................................... 6 1.1.2 Data Modeling In the Context of Database Design................................................................ 6 1.1.3 Components of A Data Model................................................................................................ 6 1.1.4 Why is Data Modeling Important? ......................................................................................... 6 1.1.5 Summary ................................................................................................................................ 7 1.2 The Entity-Relationship Model ...................................................................................................... 7 1.2.1 Basic Constructs of E-R......

Words: 16719 - Pages: 67

Premium Essay

Database Management

...1 Introduction to Databases LESSON 1 Database Learning Objectives: On completion of Lesson 1, you should have been able to: 1. Describe the role of a database system 2. Briefly describe the evolution of database systems and the limitations of conventional file processing systems 3. Describe the three schema architecture for database and explain the difference between conceptual , external and physical schemas 4. Define the functions of a database administrator Keywords and Phrases LEARNER Database Database System Entities Conceptual Model Logical Model Physical Model Constraints Metadata Database Management System File System Indexing Introduction This module introduces the reader to the different concepts of databases. It also tackles a brief history how automated databases came into existence. A number of advantages is discussed why the evolution of database management system is very much appreciated by system developers nowadays. 2 What is a Database ? Let us try to get the answers from the different Database Management System book authors. Answer from Pratt/Adamski: o A Database (DB) is structure that can store information about: 1. multiple types of entities, 2. the attributes that describe those entities; and 3. the relationships among the entities Answer from Elmasri/Navathe: o A Database (DB) is collection of related data - with the following properties: 1. A DB is logically coherent and has some relevant meaning 2. A DB is designed,......

Words: 6349 - Pages: 26

Premium Essay

Information

...2013 Logical Design, Part I In this assignment, I will write a two to three page paper titled “Logical Design, Part 1” whereas I am a recently hired consultant for ACME Global Consulting to procure requirements for a large database. In this scenario, “Logical Design, Part 1”, I will develop a database management systems to convince a set of clients of the benefits of using the Entity–Relationship model (E-R) in developing a database. In addition, my management would like the following points addressed in my design: (1). List the advantages of a relational model specific to ACME Global Consulting. (2). Summarize the purpose of an Entity–Relationship Model (E-R) specific to ACME Global Consulting. (3). List and describe essential components of the model such as entities, attributes, keys, relationships, roles, and dependencies specific to ACME Global Consulting. (4). Describe the need for the enhanced E-R model and how we can create sophisticated models to help us in complex environments. (5). Outline and describe the advantage of using the relational model. (6). Create an E-R diagram using graphical depicting software that could theoretically be used in a restaurant application. Now that you know the purpose of this assignment, I will define three key terms that will be discussed in this assignment. The first term is Database (DB), which is a collection of information organized in such a way that a computer program can quickly select desired pieces of data. You can think of......

Words: 1493 - Pages: 6

Premium Essay

Top Down Network Design

...CA218 Introduction to Databases Notes Chapter 4: Entity-Relationship (ER) Data Modelling • • • • • Introduction ER Definitions ER Notation Relationships ER Examples (c) Martin Crane 2011 CA218 Introduction to Databases Notes Introduction to ER Modelling • • • • • An Entity-relationship model (ERM) is an abstract and conceptual representation of data. ER modelling is a DB modelling method, used to produce a type of conceptual schema of a system. Diagrams created by this process are called ER diagrams. Sequence: Conceptual data model (i.e. ER) is, at a later stage (called logical design), mapped to a logical data model, (e.g. relational model); this is mapped to a physical model in physical design. ER Model used to interpret, specify & document requirements for DBs irrespective of DBMS being used. Planning/ Analysis Data Model (ER Diagram) Logical DB Conceptual Design Logical Data Model (Relational, Normal Form) Physical DB Design Physical Data Model (Tables with P., F. Keys etc) Implementation (c) Martin Crane 2011 CA218 Introduction to Databases Notes • Entity (Instance): ER Definitions Student – An instance of a physical object in the real world. – Entity Class: Group of objects of the same type. – E.g. Entity Class “Student”, Entities “John”, “Trish” etc • Attributes: – Properties of Entities that describe their characteristics. – Types: • Simple: Attribute that is not divisible, e.g. age. • Composite: Attribute...

Words: 1936 - Pages: 8