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Management Information Systems By Effy Oz

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Title: Management Information Systems By Effy Oz


1
Management Information SystemsBy Effy Oz Andy
Jones
Chapter 6 Databases and Data Warehouses
www.cengage.co.uk/oz
2
Objectives
  • Explain the difference between traditional file
    organisation and the database approach to
    managing digital data
  • Explain how relational and object oriented
    database management systems are used to construct
    databases, populate them with data, and
    manipulate the data to produce information
  • Enumerate the most important features and
    operations of a relational database, the most
    popular database model

3
Objectives (continued)
  • Understand how data modeling and design creates a
    conceptual blueprint of a database
  • Discuss how databases are used on the Web
  • List the operations involved in transferring data
    from transactional databases to data warehouses

4
Managing Digital Data
  • Businesses collect and dissect data
  • Data can be stored in powerful database format
  • Easy access and manipulation
  • Databases have profound impact on business
  • Database technology integrated with Internet

5
The Traditional File Approach
  • Traditional file approach no mechanism for
    manipulating data
  • Database approach has mechanism for manipulating
    data
  • Traditional approach inconvenient
  • High data redundancy
  • Low data integrity
  • Data redundancy duplication of data
  • Data integrity accuracy of data

6
The Traditional File Approach (continued)
7
The Database Approach
  • Database approach data organised as entities
  • Entity object that has data
  • People
  • Events
  • Products
  • Character smallest piece of data
  • Field single piece of information about entity
  • Record collection of fields

8
The Database Approach (continued)
  • File collection of related records
  • Database management system (DBMS) program used
    to build databases
  • Populates with data
  • Manipulates data
  • Query message requesting access to data

9
The Database Approach (continued)
  • Database has security issues
  • Database administrator (DBA) limits user access
    to database
  • Requires users to enter codes
  • DBMS bundled with fourth-generation languages

10
The Database Approach (continued)
11
The Database Approach (continued)
12
The Database Approach (continued)
13
Database Models
  • Database model general logical structure
  • How records stored in database
  • Records linked differently in different models
  • Models constantly changing

14
The Relational Model
  • Relational Model consists of tables
  • Based on relational algebra
  • Tuple record
  • Attribute field
  • Relation table
  • Key identifier field
  • Used to retrieve records

15
Relational Model (continued)
16
The Relational Model (continued)
  • Primary key unique key
  • Uniquely identifies record
  • Required in table
  • Composite key combination of fields
  • Serves as primary key
  • Foreign key shared field
  • Links tables
  • Join table composite of tables

17
The Relational Model (continued)
18
The Relational Model (continued)
  • Table relationships with other tables
  • One-to-many relationship one item in table
    linked to many items in other table
  • Many-to-many relationship many items in table
    linked to many items of other table

19
The Object-Oriented Model
  • Object-Oriented model uses object-oriented
    approach
  • Encapsulation combined storage of data and
    relevant procedures
  • Allows object to be planted in different data
    sets
  • Inheritance creates new object by replicating
    characteristics of existing (parent) object

20
The Object-Oriented Model (continued)
21
Relational Operations
  • Relational operation create temporary subset of
    table
  • Create limited list or joined table list
  • Select records based on conditions
  • Project columns
  • Join tables to create temporary table

22
Structured Query Language
  • Structured query language language of choice for
    DBMSs
  • Advantages
  • Standardised language
  • Used in many host languages
  • Portable

23
The Schema and Metadata
  • Schema plan
  • Describes structure of database
  • Names and sizes of fields
  • Identifies primary keys
  • Data dictionary repository of information about
    data

24
The Schema and Metadata (continued)
  • Metadata data about data
  • Source of data
  • Tables related to data
  • Field information
  • Usage of data
  • Population rules

25
The Schema and Metadata (continued)
26
Data Modeling
  • Databases must be carefully planned
  • Data modeling analysis and organisation of data
  • Proactive process
  • Develop conceptual blueprint
  • Entity relationship diagram graphical
    representation of relationships

27
Data Modeling (continued)
  • Entity relationship diagram
  • Boxes identify entities
  • Lines indicate relationship
  • Crossbars indicate mandatory fields
  • Circles indicate optional
  • Crows feet identify many

28
Data Modeling (continued)
29
Data Modeling (continued)
30
Databases on the Web
  • Web dependent on databases
  • Interface between Web and database required
  • CGI
  • ASP
  • API

31
Databases on the Web (continued)
32
Data Warehousing
  • Data collections used for transactions
  • Accumulation of transaction data useful
  • Data warehouse large database
  • Typically relational
  • Supports decision making
  • Data copied from transactional database
  • Data mart collection of data focusing on
    particular subject

33
From Database to Data Warehouse
  • Transactional database not suitable for business
    analysis
  • Only current data
  • Not historic
  • Data warehouse requires large storage capacity
  • Mainframe computers used
  • Scalability issue

34
Phases in Building a Data Warehouse
  • Begin building data warehouse after equipment
    secured
  • Extraction phase
  • Create files from transactional database
  • Transformation phase
  • Cleanse and modify data
  • Loading phase
  • Transfer files to data warehouse

35
Phases in Building a Data Warehouse (continued)
36
Summary
  • organisations collect vast amounts of data
  • Database approach has advantages over traditional
    approach
  • Character smallest piece of data
  • File collection of records
  • Designer must construct schema to construct
    database

37
Summary (continued)
  • Database management system enables database
    construction and manipulation
  • Relational and object-oriented database models
    have different advantages
  • Keys used to form links among entities
  • Object-oriented database maintains links
    differently
  • SQL adopted as international standard

38
Summary (continued)
  • Designers conduct data modeling to show required
    tables
  • Databases often linked to Web
  • Data warehouses contain huge collections of
    historical data
  • Data warehouse allows data extraction,
    transformation, and loading
  • Invasion of privacy is exacerbated by database
    technology
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