Lecture Notes #8

Transcription

Lecture Notes #8

Databases and Information Management
Reading:
Laudon & Laudon
chapter 5
Additional Reading:
Brien & Marakas
chapter 3-4
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Outline
Database Approach to Data Management
Database Management Systems
Improving Business Performance and
Decision Making

Data Warehouse
Data Marts
Business Intelligence
Managing Data Resources
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Database Approach
¾ Database

Collection of related files containing records on people, places, or
things
Prior to digital databases, business used file cabinets with paper
files
¾ Entity

Generalized category representing person, place, thing on which
we store and maintain information
Example → SUPPLIER, PART
¾ Attributes

Specific characteristics of each entity,example
SUPPLIER name, address
PART description, unit price, supplier
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Relational Database
¾Organize Data into 2D Tables

Tables → Relations with columns and rows
One table for each entity
Example → CUSTOMER, SUPPLIER, PART, SALES

Fields (columns) store data representing an attribute
Rows store data for separate records
Key field: Uniquely identifies each record

Primary key:

One field in each table
Cannot be duplicated
Provides unique identifier for all information in any row
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Relational Database
¾ Relational Database Table
A relational database organizes data in the form of two-dimensional tables. Illustrated here is a table for the
entity SUPPLIER showing how it represents the entity and its attributes. Supplier_Number is the key field.
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Relational Database
¾ Part Table
Data for the entity PART have their own separate table. Part_Number is the primary key and Supplier_Number is the foreign key,
enabling users to find related information from the SUPPLIER table about the supplier for each part.
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Relational Database
¾Establishing Relationships

Entity-relationship diagram
used to clarify table relationships in a relational database

Relational database tables may have:
One-to-one relationship
One-to-many relationship
Many-to-many relationship

Requires creating a table (join table, Intersection relation) that
links the two tables to join information
¾A Simple Entity Relationship Diagram

Relationship between supplier and Part
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Relational Database
¾ Sample Order Report
The shaded areas show which data came from the SUPPLIER, LINE_ITEM, and ORDER tables. The database does not
maintain data on Extended Price or Order Total because they can be derived from other data in the tables.
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Relational Database
¾ Final Database Design with Sample Records
The final design of the database for suppliers, parts, and orders has four tables. The LINE_ITEM table is a join table that eliminates the
many-to-many relationship between ORDER and PART.
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Relational Database
¾ Entity-Relationship Diagram for the Database with four Tables
This diagram shows the relationship between the entities SUPPLIER, ART, LINE_ITEM, and ORDER.
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Relational Database
¾Normalization

Process of streamlining complex groups of data to

Minimize redundant data elements
Minimize awkward many-to-many relationships
Increase stability and flexibility
¾Referential Entity Rules

Used by relational databases to ensure that
relationships between coupled tables remain consistent
Example → When one table has a foreign key that points to
another table, you may not add a record to the table with foreign
key unless there is a corresponding record in the linked table
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¾DBMS

Specific type of software for creating, storing,
organizing, and accessing data from a database

Separates the logical and physical views of the data

Logical view → How end users view data

Physical view → How data are actually structured and
organized
Examples of DBMS → Microsoft Access, DB2, Oracle
Database, Microsoft SQL Server, MySQL (Open Source)
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¾HRD Database with Multiple Views

Combine tables to deliver data → Users
Requirement → Two tables share a common data element
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¾Operations of a Relational DBMS

Select
Creates a subset of all records meeting stated criteria

Join
Combines relational tables to present the ser with more
information than is available from individual tables

Project
Creates a subset consisting of columns in a table
Permits user to create new tables containing only desired
information
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¾ Three Basic Operations of a Relational DBMS
The select, project, and join operations enable data from two different tables to be combined and only selected attributes to be displayed.
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¾Capabilities of DBMS

Data Definition Capabilities
Specify Structure of Contents of Database

Data Directory
Automated or manual file storing definitions of data elements
and their characteristics

Query and Data Reporting
Data manipulation language

Structured query language (SQL)
Microsoft Access query-building tools
Report generation, example → Crystal Reports
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¾ Access Data Directory Features
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¾ Example of SQL Query
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¾ An Access Query
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¾ An Access Query
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¾ Object-Oriented Database

DBMS designed for structured data rows/columns
Not suitable for graphics-based or multimedia applications
Object-oriented Database

OODBMS →Stores data and procedures that act on those data as
objects to be retrieved and shared
Usage → Manage multimedia components, Java applets for Web
Relatively slow compared to relational DBMS
Hybrid Object-relational DBMS → Provide capabilities of both types
¾ Databases

Improves Performance, Better Decisions
Tools

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Data warehousing
Multidimensional data analysis
Data mining
Utilizing Web interfaces to databases
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Using Database to Improve Performance
¾Data Warehouse

Database that stores current and historical data that
may be of interest to decision makers
Consolidates and standardizes data from many
systems, operational and transactional databases
Data can be accessed but not altered
¾Data Marts

Subset of data warehouses that is highly focused and
isolated for a specific population of users
Can be constructed more quickly at lower cost
Example – Company might develop Marketing and
Sales Data Mart to deal with customer information
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¾ Components of Data Warehouse
The data are combined with data from external sources and reorganized into a central database designed for management
reporting and analysis. The information directory provides users with information about the data available in the warehouse.
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¾ Business Intelligence

Tools for consolidating, analyzing, and providing access to large
amounts of data to improve decision making
Software for database reporting and querying
Tools for multidimensional data analysis (online analytical processing)
Data Mining
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¾Data Mining

Finds hidden patterns, relationships in large databases
and infers rules from them to predict future behavior

Types of Information
Associations → Occurrences linked to single event

Example → Chips with Coke for 65% but 85% when promotion for Coke
Sequences → Events linked over time

Example → House purchasing followed by new refrigerator 65% within 2
weeks, oven 45% within one month
Classifications → Patterns describing a group an item belongs to

Example → Characteristics of customers who are likely to leave, campaign
Clusters → Discovering as yet unclassified groupings
Forecasting → Uses series of values to forecast future values
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¾Data Mining

Applications for all functional areas of business
Government, Scientific Applications

Usage
Patterns in Customer Data → Identifying profitable customers
or for one-to-one marketing campaigns
Predictive Analysis → Using data mining techniques, historical
data, and assumptions about future conditions to predict
outcomes of events, such as the probability a customer will
respond to an offer or purchase a specific product
¾Privacy Concerns

Usage
Create detailed data image about each individual
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Case Study – DNA Databases
¾ Crime Fighting Weapon or Threat to Privacy?
¾ Questions

What are the benefits of DNA databases?

What problems do DNA databases pose?

Who should be included in a national DNA database?
Should it be limited to convicted felons? Explain your
answer.

Who should be able to use DNA databases?
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¾ Databases and the web

Information from Internal Databases → Customers
View Product Catalog, Place Order

Request from HTML Commands → SQL for DBMS Processing (database
server)
Software make this possible
Web server
Application servers or CGI
Database server

Advantage of using web to access internal databases
Much less training to employees
Few or no changes in internal databases
Savings over redesigning and rebuilding legacy systems
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¾ Policies and Procedures for Data Management

Information Policy
Organization’s rules → Sharing, Disseminating, Acquiring, Classifying,
Inventorying information
Example → Right to change/view sensitive employee data

Data Administration
Database design and management group responsible for defining and
organizing the structure and content of the database, and maintaining
the database
Specific policies and procedures for data management
Responsibilities → Developing information policy, defining and
organizing structure and content of database, planning for data, data
directory development, Overseeing logical database design
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¾ Ensuring Data Quality

Poor Data Quality
Major problem for successful customer management relationship
About 20% of US mail and packages are returned because of incorrect
names or addresses

Why Data Quality Problems?
Redundant and inconsistent data produced by multiple systems
Data input errors → Major data quality problems

Data Quality Audit
Structured survey of the accuracy and completeness of data

Data Cleansing
Detects and corrects incorrect, incomplete, improperly formatted, and
redundant data
Specialized data cleansing software → Automatically survey data files,
correct errors in the data, integrate data into company wide format
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