IS410Chap1,2,3

• an organized collection of logically related data
• – storehouse of the data

stored representations of objects and events that have meaning and importance in the user's environment

data processed to increase knowledge in the person using the data

• -Each application programmer must maintain their own data
• -Each application program needs to include code for the metadata of each file
• -Each application program must have its own processing routines for reading, inserting, updating and deleting data
• -Lack of coordination and central control
• -Non-standard file formats
• -Waste of space to have duplicate data
• -Causes more maintenance headaches
• Biggest prob:
• -When data changes in one file, could cause inconsistencies -Compromises data integrity

data that describes the properties and context of user data

• A software system that is used to create, maintain, and provide controlled access to user databases
• – software for managing the database

• -program-data independence
• -minimal data redundancy
• -improved data consistency
• -improved data sharing
• -increased productivity of application development
• -enforcement of standards-improved data quality
• -improved data accessibility and responsiveness
• -reduced program maintenance
• -improved decision support

-All programs maintain metadata for each file they use

• -new, specialized personnel
• -installation and mgmt cost and complexity
• -conversion costs
• -need for explicit backup and recovery
• -organizational conflict

• -CASE Tools
• -Repository
• -Database Management System (DBMS)
• -Database
• -Application Programs
• -User Interface
• -Data Administrators
• -System Developers
• -End Users

– computer-aided software engineering

– centralized storehouse of metadata

– software using the data

– personnel responsible for maintaining the database

– text and graphical displays to users

– personnel responsible for designing databases and software

-people who use the applications and databases

• -Program-Data Dependence
• -Duplication of Data
• -Limited Data Sharing
• -Lengthy Development Times
• -Excessive Program Maintenance

-Conceptual blueprint for organization’s desired information systems structure

• -data
• -processes
• -data network
• -people
• -events and points in time
• -reasons

describes the high-level entities in an organization and the relationship between these entities

• Decomposition
• Planning Matrixes
• E-R diagram

breaking large tasks into smaller tasks in a hierachical structure chart

• -Describe relationships between planning objects in the organization
• -Function-to-data entity

• -System development life cycle
• -Prototyping

• -the traditional methodology used to develop, maintain, and replace information systems
• -Detailed, well-planned development process
• -Time-consuming, but comprehensive
• -Long development cycle

• an iterative process of systems development in which requirements are converted to a working system that is continually revised through close work between analysts and users
• Rapid application development (RAD) method

• External Schema
• Conceptual Schema
• Internal Schema

• or data model
• is a detailed specification of the overall structure of organizational data that is independent of any database management technology
• a E-R diagram

• consists of logical schemas: relational schema (tables, columns)
• and physical schemas: implemented in a specific DBMS (column types, indexes)

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

• Must be:
• -Related to business, not technical, characteristics
• -Meaningful and self-documenting
• -Unique
• -Readable
• -Composed of words from an approved list
• -Repeatable
• -Follow a standard syntax

word or phrase with specific meaning

association between two or more terms

• -Gathered in conjunction with systems requirements
• -Accompanied by diagrams
• -Iteratively created and refined
• -Achieved by consensus

collection of entities (often corresponds to a table)

person, place, object, event, concept (often corresponds to a row in a table)

• -SHOULD BE:
• -An object that will have many instances in the database
• -An object that will be composed of multiple attributes
• -An object that we are trying to model
• -SHOULD NOT BE:
• -A user of the database system
• -An output of the database system (e.g. a report)

• property or characteristic of an entity type
• E.g., customer’s address, name, phone number

• An attribute (or combination of attributes) that uniquely identifies individual instances of an entity type
• Represented by underlining attribute name.

• -Will not change in value (name?)
• -Will not be optional (can not be address)
• -Not multi-valued (not phone numbers)
• -No intelligent identifiers (e.g. containing addresses that might change)
• -Substitute new, simple keys for long, composite keys (cust_ID generated by DBMS vs. customer name + address)

• An association representing an interaction among instances of entities that must be stored in the database (often as an event)
• Use lines to link entities with relationship

• a relationship between the instances of a single entity type
• e.g. an employee manages many employee

relationship between three entity types

-Identifies number of entity instances of entity B associated with each entity instance of entity A

Each entity A in the relationship will have exactly one related entity B and vice versa

• An entity on one side of the relationship can have many related entities, but an entity on the other side will have a maximum of one related entity
• -Represented by crow’s foot sign at many entity side

• -Entities on both sides of the relationship can have many related entities on the other side
• -Represented by adding two crow’s foot sign

• -If zero, then optional, represented by a circle
• -If one or more, then mandatory, represented by a vertical line
• -Each entity may have different constraints

• -If 1, represented by a vertical line
• -If more than 1, represented by crow’s foot.
• -Mark in min, max order from the middle

• -Exist independently of other types of entities
• -Has its own unique identifier
• -Represented with single-line rectangle

• -Dependent on a strong entity…cannot exist on its own
• -Does not have a unique identifier
• -Represented with double-line rectangle
• -Links strong entities to weak entities

an entity type that associates the instances of one or more entity types and contains attributes that are peculiar to the relationsip between those entit instances