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Learning Outcomes
Define the fundamental concepts of the relational database model
Evaluate the advantages of the relational database model
Compare operational integrity constraints and business-critical integrity constraints
Describe the role and purpose of a database management system
List and describe the four components of a database management system
Describe the two primary methods for integrating information across multiple databases
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Overview
Information is stored in databases Database – maintains information about
various types of objects (inventory), events (transactions), people (employees), and places (warehouses)
Almost every business decision isbased on information
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Database Models
Hierarchical database – stores related information in terms of predefined categorical relationships in a “tree-like” fashion
Network database – used by a network installation tool to allocate and track network resources
Relational database model – stores information in the form of logically related two-dimensional tables
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Entities, Entity Classes, and Attributes
Entity – a person, place, thing, transaction, or event about which information is stored The rows in each table contain the entities Entity includes Dave’s Sub Shop and Pizza Palace entities
[Figure 2.6 – CUSTOMER] Entity class (table) – a collection of similar entities
Entity classes include CUSTOMER, ORDER, ORDER LINE, DISTRIBUTOR, and PRODUCT
Attributes (fields, columns) – characteristics or properties of an entity class The columns in each table contain the attributes Attributes for CUSTOMER include Customer ID, Customer
Name, Contact Name, and Phone
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Keys and Relationships
Primary key – a field (or group of fields) that uniquely identifies a given entity in a table
Foreign key – a primary key of one table that appears an attribute in another table and acts to provide a logical relationship among the two tables
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Relational Database Advantagesfrom a business perspective Increased flexibility Increased scalability and performance Reduced information redundancy Increased information integrity (quality) Increased information security
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Increased Flexibility
A well-designed database should: Handle changes quickly and easily Provide users with different views A database has only one physical view
Physical view – deals with the physical storage of information on a storage device such as a hard disk
A database can have multiple logical views Logical view – focuses on how users logically
access information to meet particular business needs
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Increased Scalability and Performance
A database must scale to meet increased demand, while maintaining acceptable performance levels
Scalability – refers to how well a system can adapt to increased demands
Performance – measures how quickly a system performs a certain process or transaction
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Reduced Information Redundancy
Databases reduce information redundancy Redundancy – the duplication of information
or storing the same information in multiple places
Inconsistency is one of the primary problems with redundant information
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Increase Information Integrity
Information integrity – a measure of the quality of information
Integrity constraints – rules that help ensure the quality of information Operational integrity constraints – rules that
enforce basic and fundamental information-based constraints
Business-critical integrity constraints – rules that enforce business rules vital to an organization’s success and often require more insight and knowledge than operational integrity constraints
Users cannot create an orderfor a nonexistent customer
Product returns are not accepted forfresh product 15 days after purchase
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Increased Information Security
Information is an organizational asset and must be protected
Databases offer several security features including: Passwords – provide authentication of the
user Access levels – determine who has access to
the different types of information Access controls – Determine types of user
access, such as read-only access
Database management systems (DBMS) – software through which users and application programs interact with a database
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Data Definition Component
helps create and maintain the data dictionary and the structure of the database
Data dictionary – a file that stores definitions of information types, identifies the primary and foreign keys, and maintains the relationships among the tables
The data dictionary essentially defines the logical properties of the information that the database contains
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Data Manipulation Component
Data manipulation component – allows users to create, read, update, and delete information in a database
A DBMS contains several data manipulation tools: Views – Allows users to see, change, sort, and
query the database content Report generators Query-by-example (QBE) Structured query language (SQL)
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Application Generation and Data Administration Components Application generation component –
includes tools for creating visually appealing and easy-to-use applications
Data administration component – provides tools for managing the overall database environment by providing faculties for backup, recovery, security, and performance
IT specialists primarily use these components
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Integrating Information among Multiple Databases Organizations typically maintain multiple systems,
each with its own database Integration – allows separate systems to
communicate directly with each other Forward integration – takes information entered into
a given system and sends it automatically to all downstream systems and processes
Backward integration – takes information entered into a given system and sends it automatically to all upstream systems and processes
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Opening Case Study Questions - Searching for Revenue - Google
1. Identify the different types of entity classes that might be stored in Google’s indexing database
2. Explain why database technology is so important to Google’s business model
3. Explain the difference between logical and physical views and why logical views are important to Google’s employees