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O'Brien MIS, 6th ed.

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Title: O'Brien MIS, 6th ed.


1
Module
3
The concept of data processing Major issues in
database management
2
Learning Objectives
  • Explain the importance of implementing data
    resource management processes and technologies in
    an organization.
  • Understand the advantages of a database
    management approach to managing the data
    resources of a business.

3
Learning Objectives (continued)
  • Explain how database management software helps
    business professionals and supports the
    operations and management of a business.
  • Illustrate each of the following concepts
  • Major types of databases
  • Data warehouses and data mining
  • Logical data elements
  • Fundamental database structures
  • Database access methods
  • Database development

4
Section I
  • Managing Data Resources

5
Data Resource Management
  • A managerial activity
  • Applies information systems technology to
    managing data resources to meet needs of business
    stakeholders.

6
Foundation Data Concepts
  • Levels of data
  • Character
  • Single alphabetical, numeric, or other symbol
  • Field
  • Groupings of characters
  • Represents an attribute of some entity

7
Foundation Data Concepts (continued)
  • Records
  • Related fields of data
  • Collection of attributes that describe an entity
  • Fixed-length or variable-length

8
Foundation Data Concepts (continued)
  • Files (table)
  • A group of related records
  • Classified by
  • Primary use
  • Type of data
  • permanence

9
Foundation Data Concepts (continued)
  • Database
  • Integrated collection of logically related data
    elements
  • Consolidates records into a common pool of data
    elements
  • Data is independent of the application program
    using them and type of storage device

10
Foundation Data Concepts (continued)
  • Logical Data Elements

11
Types of Databases
  • Operational
  • Supports business processes and operations
  • Also called subject-area databases, transaction
    databases, and production databases

12
Types of Databases (continued)
  • Distributed
  • Replicated and distributed copies or parts of
    databases on network servers at a variety of
    sites.
  • Done to improve database performance and security

13
Types of Databases (continued)
  • External
  • Available for a fee from commercial sources or
    with or without charge on the Internet or World
    Wide Web
  • Hypermedia
  • Hyperlinked pages of multimedia

14
Data Warehouses and Data Mining
  • Data warehouse
  • Stores data extracted from operational, external,
    or other databases of an organization
  • Central source of structured data
  • May be subdivided into data marts

15
Data Warehouses and Data Mining (continued)
  • Data mining
  • A major use of data warehouse databases
  • Data is analyzed to reveal hidden correlations,
    patterns, and trends

16
Database Management Approach
  • Consolidates data records and objects into
    databases that can be accessed by many different
    application programs

17
Database Management Approach (continued)
  • Database Management System
  • Software interface between users and databases
  • Controls creation, maintenance, and use of the
    database

18
Database Management Approach (continued)
19
Database Management Approach (continued)
  • Database Interrogation
  • Query
  • Supports ad hoc requests
  • Tells the software how you want to organize the
    data
  • SQL queries
  • Graphical (GUI) natural queries

20
Database Management Approach (continued)
  • Report Generator
  • Turns results of query into a useable report
  • Database Maintenance
  • Updating and correcting data

21
Database Management Approach (continued)
  • Application Development
  • Data manipulation language
  • Data entry screens, forms, reports, or web pages

22
Implementing Data Resource Management
  • Database Administration
  • Develop and maintain the data dictionary
  • Design and monitor performance of databases
  • Enforce database use and security standards

23
Implementing Data Resource Management (continued)
  • Data Planning
  • Corporate planning and analysis function
  • Developing the overall data architecture

24
Implementing Data Resource Management (continued)
  • Data Administration
  • Standardize collection, storage, and
    dissemination of data to end users
  • Focused on supporting business processes and
    strategic business objectives
  • May include developing policy and setting
    standards

25
Implementing Data Resource Management (continued)
  • Challenges
  • Technologically complex
  • Vast amounts of data
  • Vulnerability to fraud, errors, and failures

26
Section II
  • Technical Foundations of Database Management

27
Database Structures
  • Hierarchical
  • Treelike
  • One-to-many relationship
  • Used for structured, routine types of transaction
    processing

28
Database Structures (continued)
  • Network
  • More complex
  • Many-to-many relationship
  • More flexible but doesnt support ad hoc requests
    well

29
Database Structures (continued)
  • Relational
  • Data elements stored in simple tables
  • Can link data elements from various tables
  • Very supportive of ad hoc requests but slower at
    processing large amounts of data than
    hierarchical or network models

30
Database Structures (continued)
  • Multi-Dimensional
  • A variation of the relational model
  • Cubes of data and cubes within cubes
  • Popular for online analytical processing (OLAP)
    applications

31
Database Structures (continued)
32
Database Structures (continued)
  • Object-oriented
  • Key technology of multimedia web-based
    applications
  • Good for complex, high-volume applications

33
Database Structures (continued)
34
Accessing Databases
  • Key fields (primary key)
  • A field unique to each record so it can be
    distinguished from all other records in a table

35
Accessing Databases (continued)
  • Sequential access
  • Data is stored and accessed in a sequence
    according to a key field
  • Good for periodic processing of a large volume of
    data, but updating with new transactions can be
    troublesome

36
Accessing Databases (continued)
  • Direct access
  • Methods
  • Key transformation
  • Index
  • Indexed sequential access

37
Database Development
  • Data dictionary
  • Directory containing metadata (data about data)
  • Structure
  • Data elements
  • Interrelationships
  • Information regarding access and use
  • Maintenance security issues

38
Database Development (continued)
  • Data Planning Database Design
  • Planning Design Process
  • Enterprise model
  • Entity relationship diagrams (ERDs)
  • Data modeling
  • Develop logical framework for the physical design

39
Discussion Questions
  • How should an e-business enterprise store,
    access, and distribute data information about
    their internal operations external environment?
  • What roles do database management, data
    administration, and data planning play in
    managing data as a business resource?

40
Discussion Questions (continued)
  • What are the advantages of a database management
    approach to organizing, accessing, and managing
    an organizations data resources?
  • What is the role of a database management system
    in an e-business information system?

41
Discussion Questions (continued)
  • Databases of information about a firms internal
    operations were formerly the only databases that
    were considered to be important to a business.
    What other kinds of databases are important for a
    business today?
  • What are the benefits and limitations of the
    relational database model for business
    applications?

42
Discussion Questions (continued)
  • Why is the object-oriented database model gaining
    acceptance for developing applications and
    managing the hypermedia databases at business
    websites?
  • How have the Internet, intranets, extranets, and
    the World Wide Web affected the types and uses of
    data resources available to business end users?

43
Real World Case 1 IBM versus Oracle
  • What key business strategies did Janet Perna
    implement to help IBM catch up to Oracle in the
    database management software market?
  • What is the business case for both IBMs and
    Oracles product strategy for their database
    software?

44
Real World Case 1 (continued)
  • Which approach would you recommend to a company
    seeking a database system today?
  • What do you see as the key factor to IBMs
    success?

45
Real World Case 1 (continued)
  • The case states that database software has
    become more of a commodity. Do you agree?

46
Real World Case 2 Experian Automotive
  • How do the database software tools discussed in
    this case help companies exploit their data
    resources?
  • What is the business value of the automotive
    database created by Experian?

47
Real World Case 2 (continued)
  • What other business opportunities could you
    recommend to Experian that would capitalize on
    their automotive database?
  • The case states that Experians automotive
    database has raised the hackles of privacy
    advocates. What legitimate privacy concerns and
    safeguard suggestions might be raised about this
    database and its use?

48
Real World Case 3 Shell Exploration
  • Why do companies still have problems with the
    quality of the data resources stored in their
    business information systems?
  • What is a data silo?

49
Real World Case 3 (continued)
  • How do data warehouse approaches help companies
    like Shell and OshKosh meet their data resource
    management challenges?
  • What business benefits can companies derive from
    a data warehouse approach?

50
Real World Case 4 BlueCross BlueShield Warner
Bros.
  • What is a storage area network? Why are so many
    companies installing SANs?
  • What are the reasons for the quick payback on SAN
    investments?

51
Real World Case 4 (continued)
  • What are the challenges and alternatives to SANs
    as a data storage technology?
  • What are some advantages of SANs?

52
Real World Case 5 Sherwin-Williams Krispy
Kreme
  • Tips for Managing External Data
  • Purchase external data from a reliable source
    that will do most of the refining for you and
    will work with you on contingency plans.
  • Run a test load first. A load of test data can
    pave the way for accurate production loads.

53
Real World Case 5 (continued)
  • Managing external data (continued)
  • Dont collect data until business and IT staff
    have agreed on the amount, frequency, format, and
    content of the data you need.
  • Dont acquire more data or use more data sources
    than you really need.

54
Real World Case 5 (continued)
  • Managing external data (continued)
  • Dont mingle external and homegrown data without
    adding unique identifiers to each record, in case
    you need to pull it out.
  • Dont overestimate the datas integrity. Nothing
    beats direct customer contact and tactical
    details behind the data.

55
Real World Case 5 (continued)
  • What challenges in acquiring and using data from
    external sources are identified in this case?
  • Do you prefer the Sherwin-Williams or Krispy
    Kreme approach to acquiring external data?

56
Real World Case 5 (continued)
  • What other sources of external data might a
    business use to gain valuable marketing and
    competitive intelligence?

57
CS 317 - Data Management and Information
Processing
58
What Is a Database System?
  • Database
    a very
    large, integrated collection of data.
  • Models a real-world enterprise
  • Entities (e.g., teams, games)
  • Relationships
    (e.g., The Forty-Niners are playing
    in The Superbowl)
  • More recently, also includes active components ,
    often called business logic. (e.g., the BCS
    ranking system)
  • A Database Management System (DBMS) is a software
    system designed to store, manage, and facilitate
    access to databases.

59
Database Systems Then
60
Database Systems Today
From Friendster.com on-line tour
61
Other Ways Databases Make Life Better?
  • Players could finally
    sign up for the Star

    Wars Galaxies game
    last week as Sony

    opened up registration
    to the public.
  • Once players got in to
    the game they found
    that the
    game servers
    were offline because of database
    problems.
  • Some players spent hours tuning their in-game
    characters only to find that crashes deleted all
    their hard work.
  • Source BBC News Online, July 1, 2003.

62
Other databases you may use
63
Is the WWW a DBMS?
  • Fairly sophisticated search available
  • crawler indexes pages on the web
  • Keyword-based search for pages
  • But, currently
  • data is mostly unstructured and untyped
  • search only
  • cant modify the data
  • cant get summaries, complex combinations of data
  • few guarantees provided for freshness of data,
    consistency across data items, fault tolerance,
  • Web sites typically have a DBMS in the background
    to provide these functions.
  • The picture is changing
  • New standards e.g., XML, Semantic Web can help
    data modeling
  • Research groups (e.g., at Berkeley) are working
    on providing some of this functionality across
    multiple web sites.

64
Search vs. Query
  • What if you wanted to find out which actors
    donated to John Kerrys presidential campaign?
  • Try actors donated to john kerry in your
    favorite search engine.

65
A Database Query Approach
66
Why Study Databases??
?
  • Shift from computation to information
  • always true for corporate computing
  • Web made this point for personal computing
  • more and more true for scientific computing
  • Need for DBMS has exploded in the last years
  • Corporate retail swipe/clickstreams, customer
    relationship mgmt, supply chain mgmt, data
    warehouses, etc.
  • Scientific digital libraries, Human Genome
    project, NASA Mission to Planet Earth, physical
    sensors, grid physics network
  • DBMS encompasses much of CS in a practical
    discipline
  • OS, languages, theory, AI, multimedia, logic
  • Yet traditional focus on real-world apps

67
Whats the intellectual content?
  • representing information
  • data modeling
  • languages and systems for querying data
  • complex queries with real semantics
  • over massive data sets
  • concurrency control for data manipulation
  • controlling concurrent access
  • ensuring transactional semantics
  • reliable data storage
  • maintain data semantics even if you pull the plug
  • semantics the meaning or relationship of
    meanings of a sign or set of signs

68
Describing Data Data Models
  • A data model is a collection of concepts for
    describing data.
  • A schema is a description of a particular
    collection of data, using a given data model.
  • The relational model of data is the most widely
    used model today.
  • Main concept relation, basically a table with
    rows and columns.
  • Every relation has a schema, which describes the
    columns, or fields.

69
Levels of Abstraction
Users
  • Views describe how users see the data.
  • Conceptual schema defines logical structure
  • Physical schema describes the files and indexes
    used.
  • (sometimes called the ANSI/SPARC model)

70
Example University Database
  • Conceptual schema
  • Students(sid string, name string,
    login string, age integer, gpareal)
  • Courses(cid string, cnamestring,
    creditsinteger)
  • Enrolled(sidstring, cidstring,
    gradestring)
  • External Schema (View)
  • Course_info(cidstring,enrollmentinteger)
  • Physical schema
  • Relations stored as unordered files.
  • Index on first column of Students.

71
Data Independence
  • Applications insulated from how data is
    structured and stored.
  • Logical data independence Protection from
    changes in logical structure of data.
  • Physical data independence Protection from
    changes in physical structure of data.
  • Q Why are these particularly important for DBMS?

72
Queries, Query Plans, and Operators
SELECT eid, ename, title FROM Emp E WHERE E.sal gt
50K
SELECT E.loc, AVG(E.sal) FROM Emp E GROUP BY
E.loc HAVING Count() gt 5
SELECT COUNT DISTINCT (E.eid) FROM Emp E,
Proj P, Asgn A WHERE E.eid A.eid AND P.pid
A.pid AND E.loc ltgt P.loc
  • System handles query plan generation
    optimization ensures correct execution.

Employees Projects Assignments
  • Issues view reconciliation, operator ordering,
    physical operator choice, memory management,
    access path (index) use,

73
Concurrency Control
  • Concurrent execution of user programs key to
    good DBMS performance.
  • Disk accesses frequent, pretty slow
  • Keep the CPU working on several programs
    concurrently.
  • Interleaving actions of different programs
    trouble!
  • e.g., account-transfer print statement at same
    time
  • DBMS ensures such problems dont arise.
  • Users/programmers can pretend they are using a
    single-user system. (called Isolation)
  • Thank goodness! Dont have to program very,
    very carefully.

74
Transactions ACID Properties
  • Key concept is a transaction a sequence of
    database actions (reads/writes).
  • DBMS ensures atomicity (all-or-nothing property)
    even if system crashes in the middle of a Xact.
  • Each transaction, executed completely, must take
    the DB between consistent states or must not run
    at all.
  • DBMS ensures that concurrent transactions appear
    to run in isolation.
  • DBMS ensures durability of committed Xacts even
    if system crashes.
  • Note can specify simple integrity constraints on
    the data. The DBMS enforces these.
  • Beyond this, the DBMS does not understand the
    semantics of the data.
  • Ensuring that a single transaction (run alone)
    preserves consistency is largely the users
    responsibility!

75
Ensuring Transaction Properites
  • DBMS ensures atomicity (all-or-nothing property)
    even if system crashes in the middle of a Xact.
  • DBMS ensures durability of committed Xacts even
    if system crashes.
  • Idea Keep a log (history) of all actions carried
    out by the DBMS while executing a set of Xacts
  • Before a change is made to the database, the
    corresponding log entry is forced to a safe
    location.
  • After a crash, the effects of partially executed
    transactions are undone using the log. Effects of
    committed transactions are redone using the log.
  • trickier than it sounds!

76
The Log
  • The following actions are recorded in the log
  • Ti writes an object the old value and the new
    value.
  • Log record must go to disk before the changed
    page!
  • Ti commits/aborts a log record indicating this
    action.
  • Log is often duplexed and archived on stable
    storage.
  • All log related activities (and in fact, all
    concurrency control related activities such as
    lock/unlock, dealing with deadlocks etc.) are
    handled transparently by the DBMS.

77
Structure of a DBMS
These layers must consider concurrency control
and recovery
  • A typical DBMS has a layered architecture.
  • The figure does not show the concurrency control
    and recovery components.
  • Each database system has its own variations.

78
Advantages of a DBMS
  • Data independence
  • Efficient data access
  • Data integrity security
  • Data administration
  • Concurrent access, crash recovery
  • Reduced application development time
  • So why not use them always?
  • Expensive/complicated to set up maintain
  • This cost complexity must be offset by need
  • General-purpose, not suited for special-purpose
    tasks (e.g. text search!)

79
Databases make these folks happy ...
  • DBMS vendors, programmers
  • Oracle, IBM, MS, Sybase,
  • End users in many fields
  • Business, education, science,
  • DB application programmers
  • Build enterprise applications on top of DBMSs
  • Build web services that run off DBMSs
  • Database administrators (DBAs)
  • Design logical/physical schemas
  • Handle security and authorization
  • Data availability, crash recovery
  • Database tuning as needs evolve

must understand how a DBMS works
80
Summary (part 1)
  • DBMS used to maintain, query large datasets.
  • can manipulate data and exploit semantics
  • Other benefits include
  • recovery from system crashes,
  • concurrent access,
  • quick application development,
  • data integrity and security.
  • Levels of abstraction provide data independence
  • Key when dapp/dt ltlt dplatform/dt

81
Summary, cont.
  • DBAs, DB developers the bedrock of the
    informationeconomy
  • DBMS RD represents a broad,
  • fundamental branch of the science of
    computation
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