Module 1

organized collection of logically related data

stored representations of meaningful objects and events

data processed to increase knowledge in the person using the data

data that describes the properties and context of user data

disadvantage of file-processing: All programs maintain metadata for each file they use

disadvantage of file-processing: Different systems/programs have separate copies of the same data

disadvantage of file-processing: No centralized control of data

disadvantage of file-processing: Programmers must design their own file formats

disadvantage of file-processing: 80% of information systems budget

• Central repository of shared data

• Data is managed by a controlling agent

• Stored in a standardized, convenient form

elements of database approach:

– Graphical system capturing nature and relationship of data

– Enterprise Data Model–high-level entities and relationships for the organization

– Project Data Model–more detailed view, matching data structure in database or data warehouse

elements of database approach:

– Noun form describing a person, place, object, event, or concept

– Composed of attributes

elements of database approach:

– Between entities

– Usually one-to-many (1:M) or many-to-many (M:N)

elements of database approach:

– Database technology involving tables (relations) representing entities and primary/foreign keys representing relationships

component of database approach: computer-aided software engineering

component of database approach: centralized storehouse of metadata

component of database approach: software for managing the database

component: storehouse of the data

component: software using the data

component: text and graphical displays to users

component: personnel responsible for maintaining the database

component: personnel responsible for designing databases and software

component: people who use the applications and databases

component: software using the data

–Detailed, well-planned development process

–Time-consuming, but comprehensive

–Long development cycle

–Rapid application development (RAD)

–Cursory attempt at conceptual data modeling

–Define database during development of initial prototype

–Repeat implementation and maintenance activities with new prototype versions

sdlc:

- Purpose–preliminary understanding Deliverable–request for study

- Database activity– enterprise modeling and early conceptual data modeling

sdlc:

- Purpose–thorough requirements analysis and structuring; Deliverable–functional system specifications

- Database activity–thorough and integrated conceptual data modeling

sdlc:

- Purpose–information requirements elicitation and structure Deliverable–detailed design specifications

- Database activity– design (transactions, forms, displays, views, data integrity and security)

sdlc:

- Purpose–develop technology and organizational specifications Deliverable–program/data structures, technology purchases, organization redesigns

- Database activity– physical database design (define database to DBMS, physical data organization, database processing programs)

sdlc:

- Purpose–programming, testing, training, installation, documenting Deliverable–operational programs, documentation, training materials

- Database activity– , including coded programs, documentation, installation and conversion

sdlc:

- Purpose–monitor, repair, enhance Deliverable–periodic audits

- Database activity– database maintenance, performance analysis and tuning, error corrections

prototyping: analyze requirements, develop prelimenary data model

prototyping: analyze requirements in detail, integrate database views into conceptual data model

prototyping: define new database contents to dbms, decide on physical organization for new data, design database processing programs

prototyping: code database processing, install new database contents usually from existing data sources

prototyping: analyze database to ensure it meets application needs, fix errors in database

prototyping: tune database for improved performance, fix errors in database

• User Views • Subsets of Conceptual Schema • Can be determined from business-function/data entity matrices • DBA determines schema for different users

e-r models

• Logical structures

• Physical structures

• Initiated and planned in planning stage of SDLC

• Executed during analysis, design, and implementation

• Closed at the end of implementation

a planned undertaking of related activities to reach an objective that has a beginning and an end