1 / 27

CHAPTER 8. MANAGING DATA RESOURCES

CHAPTER 8. MANAGING DATA RESOURCES. FILE ORGANIZATION. BIT: Binary Digit (0,1;Y,N;On, Off) BYTE: Combination of BITS which represent a CHARACTER FIELD: Collection of BYTES which represent a Fact RECORD: Collection of FIELDS which reflect a TRANSACTION FILE: A Collection of Similar

brian
Download Presentation

CHAPTER 8. MANAGING DATA RESOURCES

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. CHAPTER 8. MANAGING DATA RESOURCES

  2. FILE ORGANIZATION • BIT:Binary Digit (0,1;Y,N;On, Off) • BYTE:Combination of BITS which represent a CHARACTER • FIELD:Collection of BYTES which represent a Fact • RECORD:Collection of FIELDS which reflect a TRANSACTION • FILE:A Collection of Similar RECORDS

  3. The layout of a personnel file in traditional file organization. Managing Digital Data

  4. FILE ORGANIZATION • DATABASE:An Organization’s Electronic Library of FILES • Primary FIELD or Key:Field in Each Record Uniquely Identifies THIS Record ForRETRIEVAL UPDATING SORTING

  5. Different information making up a student record retained in three different sites. TRADITIONAL FILE ENVIRONMENT(FLAT FILE) • DATA REDUNDANCY • PROGRAM / DATA DEPENDENCY • LACK OF FLEXIBILITY • POOR SECURITY • LACK OF DATA SHARING & AVAILABILITY

  6. DATABASEMANAGEMENTSYSTEM(DBMS) SOFTWARE TO CREATE & MAINTAIN DATA *** ENABLES BUSINESS APPLICATIONS TO EXTRACT DATA *** INDEPENDENT OF SPECIFIC COMPUTER PROGRAMS DBMS

  7. 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

  8. COMPONENTSOFDBMS: • THE SCHEMA: describe the structure of the Database. DATA DEFINITION LANGUAGE: • Defines Data Elements in Database • and Used to construct the schema DATA MANIPULATION LANGUAGE: • Manipulates Data for Applications • DATA DICTIONARY: • Maintains all information supplied by the developer when constructing the schema * DBMS

  9. Data definition language to create a schema in NOMAD • Data Definition Language (DDL)

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

  11. A typical data dictionary for a staff file DATA DICTIONARY

  12. ADVANTAGESOFDBMS: • REDUCES COMPLEXITY • REDUCES DATA REDUNDANCY • CENTRAL CONTROL OF DATA DEFINITIONS • REDUCES PROGRAM / DATA DEPENDENCE • REDUCES DEVELOPMENT / MAINTENANCE COSTS • ENHANCES SYSTEM FLEXIBILITY • INCREASES ACCESS / AVAILABILITY OF INFORMATION * DBMS

  13. ROOT Employer Job Benefits Compensation FIRST CHILD Assignments 2nd CHILD Ratings Salary Pension Insurance Health Database Models HIERARCHICAL DATA 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

  14. NETWORK 1 NETWORK 2 NETWORK A NETWORK B NETWORK C NETWORK DATA MODEL • VARIATION OF HIERARCHICAL MODEL • Allows a record to be linked to more than one parent • USEFUL FOR MANY-TO-MANY RELATIONSHIPS

  15. RELATIONAL DATA MODEL • Consists of tables; links among entities are maintained with foreign keys • DATA IN TABLE FORMAT • RELATION: TABLE • TUPLE: ROW (RECORD) IN TABLE • FIELD: COLUMN (ATTRIBUTE) IN TABLE *

  16. STUDENT ID ONE-TO-ONE: CLASS ONE-TO-MANY: STUDENT A STUDENT B STUDENT C CLASS 1 CLASS 2 MANY-TO-MANY: STUDENT A STUDENT B STUDENT C TYPES OR RELATIONS

  17. Relational Operations • Data Manipulation • Select :is the selection of records that meets certain condition. • Project: is the selection of certain columns from a table. • Join : is the joining of data from multiple tables. • 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.

  18. Advantages and disadvantages of database models Database Models

  19. DatabaseArchitecture • 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

  20. A replicated database: each computer holds a copy of the entire database Database Architecture • Distributed Databases • Replication :Full copy of the entire database is stored at all sites

  21. A fragmented database: each computer holds only the part of the database that is most frequently accessed by the local users Database Architecture • Fragmentation: Parts of database are stored where they are most often accessed

  22. 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

  23. 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

  24. DataWarehousing

  25. Potential applications of data-mining Data-Mining

  26. DATABASEADMINISTRATION • DEFINES & ORGANIZES DATABASE STRUCTURE AND CONTENT • DEVELOPS SECURITY PROCEDURES • DEVELOPS DATABASE DOCUMENTATION • MAINTAINS DBMS *

  27. Ethical and Societal IssuesA 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. • http://www.publicrecordfinder.com/ • The Upside • Database technology enables better and faster services.

More Related