Data Management Options Dr. Merle P. Martin MIS Department CSU Sacramento

Acknowledgments t Dr. Russell Ching ( MIS Dept ) Source Materiel / Graphics t Edie Schmidt ( UMS ) - Graphic Design t Prentice Hall Publishing (Permissions) u Martin, Analysis and Design of Business Information Systems, 1995

Agenda t Why manage data? t Definitions t Typical problems t Data Administrator t The DBMS t Distributing data

Why Manage Data? t Delayed output ( paycheck ) t Locate a resource u Where is the stock item stored? u Where does the employee work?

Why Manage Data? t Make resource decisions u Should we turn account over to collection agency? u Should we send customer letter asking why he / she hasn’t shopped here in 6 months? u Should we give employee overtime?

Why Manage Data? t Determine resource status u Is there enough stock in warehouse to satisfy this customer’s order? u How much should I order? u What is the value of this resource? v balance sheet

Definitions t File: resource inventory: u Material u People v Employees, customers u Funds v Customer balances v Accounts Payable

Definitions t Data Organization u Bit / byte u Character u Field u Record u File u DBMS

Data Hierarchy for Stereos to Go 12345SmithJohnA123 Main StreetSacramentoCA SmithJohnA123 Main StreetSacramentoCA SmithJohnA123 Main StreetSacramentoCA95819 Smith Database File Record Field Character (Byte) Bit 1 { {

Definitions t Views: u Physical - how stored u Logical - how viewed and used t Volatility: - % records that change t Immediacy: rapidity of change

Storage Problems t Redundancy t Accuracy t Security t Lack of data sharing t Report inflexibility t Inconsistent data definitions t Too much data u information overload

Data Administrator t Clean up data definitions t Control shared data t Manage distributed data t Maintain data quality

Clean Up Definitions t Synonyms / aliases t Standard data definitions u names and formats u Date of Birth ( AJIS ) v mm/dd/yy ( courts ) v dd/mm/yy ( corrections ) t Data Dictionary u COBOL

Control Shared Data t Local - used by one unit t Shared - used by two or more activities t Impact of proposed program changes on shared data t Program-to-data element matrix t Control or clearinghouse?

Manage Distributed Data t Geographically dispersed u whether shared data or not t Different levels of detail u different management levels

Internal External Well defined Wide Detailed Aggregate Historical Future Quite old Very frequent Infrequent High Low Management Control Operational Control Strategic Planning Highly current Level of Aggregation Source Scope Time Horizon Currency Frequency of Use Required Accuracy

Maintain Data Quality t Put owners in charge of data u verify data accuracy and quality u Fairbanks Court example t Who owns the data?

Issue Should the Data Administrator control ALL data, or just that data that crosses organizational boundaries? WHAT DO YOU THINK?

The DBMS Data Base Management System: software that permits a firm to: u centralize data u manage them efficiently u provide access to applications v such as payroll, inventory

DBMS Components t Data Design Language ( DDL) t Data Manipulation Language ( DML ) t Inquiry Language ( IQL ) t Teleprocessing Interface ( TP ) t Martin, Figure 16-5

DatabaseDatabase TeleprocessTeleprocess InterfaceInterface DesignersDesigners DDLDDL End-UsersEnd-Users Update Retrieve IQLIQL ProgrammersProgrammers Applic. Software DMLDML

IQL LANGUAGE IQL SELECT EMP-ID, EMP-FIRST- NAME, EMP-FIRST- NAME, EMP-LAST- NAME, EMP-LAST- NAME, EMP-YTD-PAY EMP-YTD-PAY FROM EMPLOYEE FROM EMPLOYEE WHERE EMP- ID=1234 WHERE EMP- ID=1234. Data Base

3-level Database Model t James Martin t Sprague / McNurlin, Fig. 7-2, pg. 207

External Level (1) t User views ( logical) t By application program t Each has unique view t Schema / subschema

Schema and Subschemas DBMS Schema Subschema Physical Database DBMS Software Overall View of the Data Individual Views User Subschema

Enterprise Level (2) t Under control of Data Administrator t DBMS t Implementation data removed u passwords u report views

Physical Level (3) t Schema t Pointers ( e.g., next record ) t Flags ( e.g., record frozen )

Traditional Data Models t Hierarchical - one parent t Network u more than one parent u student to course, major t Relational ( tables)

Hierarchical Model 1 1 Dept. A Dept. B Dept C Project 1 Employees

Network Model John Smith SavingsSavings CheckingChecking MortgageMortgage Jane Smith

Relational Order NumberOrder DateAccount NumberDate Shipped Account NumberLast NameFirst NameCredit LimitMiddle Initial... Product CodeProduct NameUnitPriceManufacturer Code Order NumberLine Item NumberProduct CodeQuantity Manufacturer NameManufacturer Code Customer Orders Line Items Products Manufac(turer)

Object-oriented DBMS An object is: u a piece of data PLUS u procedures performed on data PLUS u attributes describing data PLUS u relationship between object and other objects

Distributed Data t Goals: u move processing as close to users as possible u allow several applications to run simultaneously on same data

Distributed Types t Fragmented u distribute data without duplication u users unaware of where data located t Segmented u data duplicated u one site has master file u problem with data synchronization

Why Distribute? t Save money u offload DB processes to less expensive machines (PCs) u Lower telecommunications costs u DB closer to users t Decrease dependence on a single computer manufacturer

Why Distribute t Move control closer to owner t Increased DBMS scope u more varied types of data u link at workstations t Permit storage of multimedia data

True Distributed DB t Local autonomy ( ownership) t No reliance on central site t Continuous operations u not affected by another site t Data transparency t Independence

Independence t Fragmentation t Replication t Hardware t Software t Networks t Database

Problems With Distributed Databases t Security t Shared data u simultaneous update t Complexity t Need telecommunications infrastructure

Issue Is data in your organization totally distributed? u How? u Should it be? u Why or why not?

Points to remember t Definition t Typical problems t Role of Data Administrator t The DBMS t Distributing data