Chapter 8 Data and Knowledge Management
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Transcript of 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.)