chapter 8 data and knowledge management

Management Information Systems, 4th Edition 1

Chapter 8Data and Knowledge Management

Management Information Systems, 4th Edition 2

Managing Digital Data• The Traditional File Approach

– Disadvantages• Program/Data Dependency

• Data Redundancy

• Data Integrity

• Moving to Databases– Database Management System (DBMS)

• Queries: Request data from specified fields

• Security: Giving users different views addresses security issue

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Managing Digital Data (Cont)

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Managing Digital Data (Cont.)

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Traditional Files vs. Databases: Pros and Cons

• Traditional File Advantages– Simplicity– Efficiency– Customization

• Database Advantages– Reduced data redundancy– Application/data independence– Better control– Flexibility

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The Hierarchical Model• Records are related hierarchically—each

category is a subcategory of the next level up

• Disadvantages of hierarchical databases

– To retrieve a record, a user must start at the root and navigate the hierarchy.

– If a link is broken, the entire branch is lost.

– Requires considerable data redundancy

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The Hierarchical Model

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The Network Model

• Allows a record to be linked to more than one parent

• Supports many-to-many relationships

• Advantage of the network model

– Reduced data redundancy

• Disadvantages of the network model

– Complicated to build and difficult to maintain

– Difficult to maintain and navigate

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The Network Model (Cont.)

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The Relational Model• Consists of tables; links among entities are

maintained with foreign keys

• Advantages of relational databases

– Same advantages of a network database without the complications

– Easier to conceptualize and maintain

– Virtually all DBMSs offered for microcomputers accommodate the relational model

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The Relational Model (Cont.)

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The Object-Oriented Structure• Useful for data and information that cannot be

organized into fields

• Does not store records, but data objects

• Advantages include ability to represent data dynamically

• Disadvantages include dependence between applications and data

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Components of Database Management Systems

• The Schema

– Describes the structure of the database

• The Data Dictionary (Metadata)

– Maintains all information supplied by the developer when constructing the schema

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Relational Databases: Design and Keys

• Data Modeling

– Analyzing data and identifying relationships

– Entity Relationship (ER) Diagram, a graphical representation of all entity relationships

– Understand symbols when reviewing a diagram

– Key: a field whose value identify records

• Primary Key

• Linking

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Relational Databases: Design and Keys (Cont.)

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Relational Databases: Design and Keys (Cont.)

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• The Schema

– Describes the structure of the db

• Names, types of fields, general relationships

– Types of data

• Numeric, alphanumeric, graphic, time-related

– Building a Database

Components of Database Management Systems

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Components of Database Management Systems (Cont.)

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• All information supplied by db developer in the schema is maintained here

– Table names

– Record names and types

– Field names and types

– Relationships among record types

– Who is responsible for updating the db

The Data Dictionary

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The Data Dictionary (Cont.)

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Data Definition Language (DDL)

• Used to construct the schema

• Usually transparent to user of modern relational DBMS

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Data Manipulation Language (DML)

• Software used to query the database

• Either enter a statement requesting information, or a Query by Example (QBE)

• Programmers use this for developing applications

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Data Manipulation Language (DML)

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Relational Operations

• Data Manipulation

– Select, Project, Join

• Structured Query Language (SQL)

– International standard DDL and DML for relational DBMS

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• SQL (cont.)

– Advantages

– Users do not need to learn different DDLs and DMLs.

– SQL can be embedded in widely used 3rd generation languages, increasing efficiency and effectiveness.

– Programmer not forced to rewrite statements since SQL statements are portable.

Relational Operations (Cont.)

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Database Architecture

• Distributed Databases

– Replication

• Full copy of the entire database is stored at all sites

– Fragmentation

• Parts of database are stored where they are most often accessed

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Database Architecture (Cont.)

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Database Architecture (Cont.)

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Client/Server Systems• Four basic client/server models

– Applications run at a server

– Applications run on local PCs

– Applications run on both the local PCs and the server

– Applications and key elements of the database are split between the PCs and the server

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Databases on the Web• Catalogs

• Libraries of books, articles, CDs, and movie clips

• Directories

• Client lists and profiles

• Package tracking

• Customer relationship management

• Financial transactions databases

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• Points to Consider

• Which application to use

• How to ensure Web surfers do not interfere with database updates

• How to maintain security

Databases on the Web (Cont.)

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Data Warehousing

• Data warehouse: a collection of data that supports management decision making

• Data Mart: smaller collection of data focusing on a particular subject or department

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• From Database to Data Warehouse

– Transactional db usually not suitable for analysis because they contain current, not historical data

– Hardware must meet capacity needs

– Data and software and scalability must be considered

Data Warehousing (Cont.)

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• Extraction Phase

– Builders create the files from transactional db and save on server

• Cleansing Phase

– Data is made consistent

• Loading Phase

– Builders transfer files to data warehouse database

Phases in Building a Data Warehouse

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Data Mining and Online Analysis

• Data mining

– Sequence or path analysis

– Classification

– Clustering

– Forecasting

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Data Mining and Online Analysis (Cont.)