- Identify the main characteristics of entity relationship components in two-three paragraphs with valid references.
Chapter 2 Data Models ‹#› 1 After completing this chapter, you will be able to: Discuss data modeling and why data models are important Describe the basic data-modeling building blocks Define what business rules are and how they influence database design Understand how the major data models evolved List emerging alternative data models and the needs they fulfill Explain how data models can be classified by their level of abstraction Learning Objectives © 2019 Cengage. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. ‹#› 2 Data modeling: creating a specific data model for a determined problem domain Data model: simple representation of complex real-world data structures Useful for supporting a specific problem domain Model: abstraction of a more complex real-world object or event Data Modeling and Data Models © 2019 Cengage. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. ‹#› 3 The importance of data modeling cannot be overstated Facilitates communication Gives various views of the database Organizes data for various users Provides an abstraction for the creation of good a database The Importance of Data Models © 2019 Cengage. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. ‹#› 4 Entity: person, place, thing, or event about which data will be collected and stored Attribute: characteristic of an entity Relationship: association among entities One-to-many (1:M OR 1..*) Many-to-many (M:N or *..*) One-to-one (1:1 OR 1..1) Constraint: restriction placed on data Ensures data integrity Data Model Basic Building Blocks © 2019 Cengage. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. ‹#› 5 Brief, precise, and unambiguous description of a policy, procedure, or principle Create and enforce actions within that organization’s environment Establish entities, relationships, and constraints Business Rules © 2019 Cengage. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. ‹#› 6 Sources of business rules Company managers Policy makers Department managers Written documentation Direct interviews with end users Discovering Business Rules (1 of 2) © 2019 Cengage. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. ‹#› 7 Reasons for identifying and documenting business rules Standardize company’s view of data Facilitate communications tool between users and designers Assist designers Understand the nature, role, scope of data, and business processes Develop appropriate relationship participation rules and constraints Create an accurate data model Discovering Business Rules (2 of 2) © 2019 Cengage. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. ‹#› 8 Business rules set the stage for the proper identification of entities, attributes, relationships, and constraints Nouns translate into entities Verbs translate into relationships among entities Relationships are bidirectional Questions to identify the relationship type How many instances of B are related to one instance of A? How many instances of A are related to one instance of B? Translating Business Rules into Data Model Components © 2019 Cengage. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. ‹#› 9 Entity name requirements Be descriptive of the objects in the business environment Use terminology that is familiar to the users Attribute name Required to be descriptive of the data represented by the attribute Proper naming Facilitates communication between parties Promotes self-documentation Naming Conventions © 2019 Cengage. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. ‹#› 10 Hierarchical models: developed to manage large amounts of data for complex manufacturing projects Represented by an upside-down tree which contains segments Segments are the equivalent of a file system’s record type Depicts a set of one-to-many (1:M) relationships Hierarchical and Network Models (1 of 2) © 2019 Cengage. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. ‹#› 11 Network models: created to represent complex data relationships effectively Improved database performance and imposed a database standard Allows a record to have more than one parent Standard database concepts that emerged with the network model are still used by modern data models Schema and subschema Data manipulation language (DML) Data definition language (DDL) Hierarchical and Network Models (2 of 2) © 2019 Cengage. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. ‹#› 12 Produced an automatic transmission database that replaced standard transmission databases Based on a relation (i.e., table): matrix composed of intersecting tuples (rows) and attributes (columns) Describes a precise set of data manipulation constructs The Relational Model (1 of 4) © 2019 Cengage. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. ‹#› 13 Relational database management system (RDBMS) Performs basic functions provided by the hierarchical and network DBMS systems Makes the relational data model easier to understand and implement Hides the complexities of the relational model from the user The Relational Model (2 of 4) © 2019 Cengage. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. ‹#› 14 The Relational Model (3 of 4) © 2019 Cengage. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. ‹#› 15 SQL-based relational database application End-user interface Allows end user to interact with the data Collection of tables stored in the database Each table is independent from another Rows in different tables are related based on common values in common attributes SQL engine Executes all queries The Relational Model (4 of 4) © 2019 Cengage. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. ‹#› 16 Graphical representation of entities and their relationships in a database structure Entity relationship diagram (ERD): uses graphic representations to model database components Entity instance or entity occurrence: rows in the relational table Attributes: describe particular characteristics Connectivity: term used to label the relationship types The Entity Relationship Model (1 of 2) © 2019 Cengage. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. ‹#› 17 The Entity Relationship Model (2 of 2) © 2019 Cengage. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. ‹#› 18 Both data and its relationships are contained in a single structure known as an object Object-oriented database management system(OODBMS): based on OODM Object: contains data and their relationships with operations that are performed on it Basic building block for autonomous structures Abstraction of real-world entity Attribute: describes the properties of an object The Object-Oriented Data Model (1 of 3) © 2019 Cengage. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. ‹#› 19 Class: collection of similar objects with shared structure and behavior organized in a class hierarchy Class hierarchy: resembles an upside-down tree in which each class has only one parent Inheritance: object inherits methods and attributes of classes above it Unified Modeling Language (UML): describes sets of diagrams and symbols to graphically model a system The Object-Oriented Data Model (2 of 3) © 2019 Cengage. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. ‹#› 20 The Object-Oriented Data Model (3 of 3) © 2019 Cengage. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. ‹#› 21 Extended relational data model (ERDM) Supports OO features, extensible data types based on classes, and inheritance Object/relational database management system (O/R DBMS): based on ERDM Extensible Markup Language (XML) Manages unstructured data for efficient and effective exchange of structured, semistructured, and unstructured data Object/Relational and XML © 2019 Cengage. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. ‹#› 22 Goals of Big Data Find new and better ways to manage large amounts of web and sensor-generated data Provide high performance at a reasonable cost Characteristics of Big Data Volume Velocity Variety Emerging Data Models: Big Data and NoSQL (1 of 3) © 2019 Cengage. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. ‹#› 23