information and databases

©1999 Addison Wesley Longman Slide 4.1

Informationand Databases

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Table 4.1Using a CAD System to Design the Boeing 777



CUSTOMER

Boeing’s manufacturing department

Airline maintenance departments



PRODUCT

Specification of the precise function, shape, and location of each component

Verification that the components are physically compatible



BUSINESS PROCESS

Major Steps:

•Decide on major features of airplane

•Design individual components

•Test for compatibility with other components and other subsystems

•Transmit the specifications to manufacturing

Rationale:

•Use a paperless design process to avoid delays related to copying and moving paper, and to use the design data directly to test for interference between components.



PARTICIPANTS

Representatives of airlines

Boeing engineers

INFORMATION

General design goals

CAD specification of the shape, location, materials, and function of each component

TECHNOLOGY

CAD database and computer for storing the data

Terminals and data network


Figure 4.1Entity-relationship diagram for part of a university registration system


Figure 4.2Types of relationships in entity-relationship


Table 4.2Possible Attributes for the Entity Types in Figure 4.1

DEPARTMENT•Department identifier•College•Department head•Scheduling coordinator

COURSE•Course number•Department •Required of department major (y/n)•Course description

SECTION•Section identification number•Semester•Year•Classroom•Start time•End time•Days of week for class meetings

PROFESSOR•Employee identification number•Name•Address•Birthdate•Office telephone•Social Security number

STUDENT•Student identification number•Name•Address•Birthdate•Telephone•Gender•Ethic group•Social Security number

OFFICE•Office number•Building•Telephone extension


Figure 4.3Images produced by information systems


Table 4.3Excerpt from a Hypothetical Student File

Social security number: 044-34-5542Last name: BatesFirst name: AlvinStreet address: 243 Third StreetCity: MiddletonState: MAZip code: 02137Date of birth: 05/07/78


Figure 4.4Entity-relationship diagram from a relational database


Figure 4.5Posing a query in Microsoft Access


Figure 4.6Using a natural language query


Figure 4.7A Multidimensional database


Figure 4.8Using a geographical information system


Figure 4.9Use of schemas and subschemas


Figure 4.10Locating data using direct access


Figure 4.11Locating data using indexes


Figure 4.12Backup and recovery


Figure 4.13Retrieving a Web page


Table 4.4Differences between Using a Relational Database and Using the World Wide Web

BASIC STRUCTURAL ELEMENTSTraditional database: Tables, records, fields, keysThe World Wide Web: Web pages and hyperlinks

BASIC ORGANIZING PRINCIPLETraditional database: Predefined tables and relationships that have a specific meaning in a specific business context The World Wide Web: Author-defined links from any location in a Web page to any other location on the same Web page or to another Web page

FINDING SPECIFIC INFORMATIONTraditional database: Identify specific records or fields in those records and the DBMS will find themThe World Wide Web: Identify a specific Web address (URL) and the browser will find and display the page if it is available

FINDING INFORMATION RELATED TO THE INFORMATION MOST RECENTLY ACCESSEDTraditional database : No typical methodThe World Wide Web : Click on a hypertext link

METHOD FOR IDENTIFYING DATA REQUIRED IN A QUERYTraditional database: State selection criteria in terms of specific values of specific data items in specific tablesThe World Wide Web: Identify words or terms that should appear in the Web pages selected by the search engine


Table 4.4Differences between Using a Relational Database and Using the World Wide Web

HOW THE COMPUTER FINDS THE DATA BY SEARCHINGTraditional database: DBMS finds the pertinent tables in the database and selects the appropriate data from the records that meet the criteriaThe World Wide Web: Search engine finds every Web page containing each word or phrase in the query, then prioritizes these based on the priorities in the query

TREATMENT OF IMPOSSIBLE OR RIDICULOUS QUERIESTraditional database: DBMS rejects queries not phrased in terms of tables, fields, and relationships in the databaseThe World Wide Web: The search engine performs whatever search is requested

LIKELIHOOD THAT A QUERY WILL PRODUCE USABLE RESULTSTraditional database: DBMS returns exactly what is requested; if the user asks the wrong question, the result may not be usefulThe World Wide Web: Many of the Web pages found by a search engine may be unrelated to what the user wanted

METHODS FOR CONTROLLING DATA QUALITYTraditional database: During data entry DBMS checks for obvious errors such as missing values, out-of-range values, etc.The World Wide Web: The Web has no organized method of controlling quality of information in Web pages


Table 4.5Determinants of Information Usefulness and Related Roles of Information Syatems

INFORMATION QUALITY

•ACCURACY

•PRECISION

•COMPLETENESS

•AGE

•TIMELINESS

•SOURCE


Table 4.5Determinants of Information Usefulness and Related Roles of Information Systems

INFORMATION ACCESSIBILITY

•AVAILABILITY

•ADMISSIBILITY

INFORMATION PRESENTATION

•LEVEL OF SUMMARIZATION

•FORMAT

INFORMATION SECURITY

•ACCESS RESTRICTION

•ENCRYPTION


Figure 4.16Do managers expect the truth?


Fig 4.17Diagram representing a mental model


Figure 4.18A virtual reality simulation

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