Chapter 8 Data and Knowledge Management

2 Learning Objectives When you finish this chapter, you will  Know the difference between traditional file organization methods and the database approach.  Know how database management systems are used to construct databases, populate them with data, and manipulate the data to produce information.  Be familiar with the different database models and the advantages and disadvantages of each model.

3 Learning Objectives  Know the most important features and operations of a relational database.  Understand how databases are changing business operations across industries and what impact they might have on our personal lives.  Understand the concepts of data warehousing and data-mining and their use in business.  Recognize the need for knowledge storage and management and be able to give examples of the ways knowledge is managed in organizations.

4 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

5 Managing Digital Data Figure 8.1 The layout of a personnel file in traditional file organization.

6 Managing Digital Data Figure 8.2 Different information making up a student record retained in three different sites.

7 Managing Digital Data Figure 8.3 Data hierarchy

8 Managing Digital Data Figure 8.4 Different database views reveal different combinations of data

9 Managing Digital Data Figure 8.5 Different views of one employee database

10 Managing Digital Data Traditional Files vs. Databases: Pros and Cons  Traditional File Advantages  Simplicity  Efficiency  Customization  Database Advantages  Reduced data redundancy  Application/data independence  Better control  Flexibility

11 Database Models Figure 8.6 Advantages and disadvantages of database models

12 Database Models 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 because child records can have only one parent

13 Database Models Figure 8.7 A schematic diagram of a hierarchical database (a) and a sample part of a hierarchical database showing relationships among different records (b)

14 Database Models The Network Model  Allows a record to be linked to more than one parent  Supports many-to-many (N:M) relationships  Advantage of the network model  Reduced data redundancy  Disadvantages of the network model  Complicated to build and difficult to maintain  Difficult to navigate

15 Database Models Figure 8.8 A schematic diagram of a network database (a) and a sample of part of a network database showing relationships among different records (b)

16 Database Models 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.

17 Database Models Figure 8.9 A schematic diagram of a relational database (a) and a sample part of a relational database showing different tables (b)

18 Database Models Keys  Fields whose values identify records for display or processing.  Primary key  Uniquely identifies a record  Linking

19 Database Models The Object-Oriented Structure  Affords maintenance of data along with the applications that process them Entity-Relationship Diagrams  Conceptual blueprint of a database  Graphical representation of all entity relationships

20 Database Models Figure 8.10 An entity-relationship diagram

21 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

22 Components of Database Management Systems Figure 8.12 A typical data dictionary for a staff file

23 Figure 8.13 Data definition language to create a schema in NOMAD Components of Database Management Systems Data Definition Language (DDL)  Used to construct the schema

24 Components of Database Management Systems Data Manipulation Language (DML)  Used to query the database Figure 8.14 A Paradox query by example

25 Relational Operations Data Manipulation  Select, Project, Join Structured Query Language (SQL)  International standard DDL and DML for relational DBMS.  Advantages of using SQL  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.

26 Relational Operations Figure 8.15 A join table of professors and their students

27 Popular Database Management Systems Figure 8.16 Popular DBMSs

28 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

29 Database Architecture Figure 8.17 A replicated database: each computer holds a copy of the entire database

30 Database Architecture Figure 8.18 A fragmented database: each computer holds only the part of the database that is most frequently accessed by the local users

31 Database Architecture Shared Resource and 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

32 Database Architecture Figure 8.19 Shared resource and client/server architectures

33 Web Databases Databases on the Web  Catalogs  Libraries  Directories  Client lists and profiles When linking a database to the Internet, consider  Which application to use  How to ensure Web surfers do not interfere with database updates  How to maintain security

34 Data Warehousing Data warehouse  Collection of data that supports management decision making  Phases in Building a Data Warehouse  Extraction Phase  Cleansing Phase  Loading Phase Data Mining  Selecting, exploring, and modeling data to discover unknown relationships

35 Data Warehousing Figure 8.20 Data are warehoused for analysis and reporting

36 Data-Mining Figure 8.21 Potential applications of data-mining

37 Knowledge Management The attempt by organizations to:  Transfer knowledge into databases  Filter and separate the most relevant knowledge  Organize knowledge in databases that either  Allow other employees to easily access the knowledge  “Push” specific knowledge to employees based on their prespecified needs

38 Ethical and Societal Issues A Too-Risky Info Highway Out of Hand -- Out of Control  DBMSs allow organizations to collect, maintain, and sell vast amounts of private personal data easily. Where is the Information Going?  Many consumers provide information daily without being aware of where it is actually going.

39 Ethical and Societal Issues A Too-Risky Info Highway Personal Data Matched, Sliced, and Diced  Pieces of personal data may be matched and put together to reveal private life in unexpected ways. Error Propagation  In case of errors, it may be impossible to trace your data to all organizations that have it. The Upside  Database technology enables better and faster services.