chap008 (1)

chap008 (1) - Context Diagram Use Case Development Data...

Info iconThis preview shows pages 1–8. Sign up to view the full content.

View Full Document Right Arrow Icon
Context Diagram – Use Case Development
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Data Modeling Data modeling – a technique for organizing and documenting a system’s data. Sometimes called database modeling . Entity relationship diagram (ERD) – a data model utilizing several notations to depict data in terms of the entities and relationships described by that data.
Background image of page 2
The Process of Logical Data Modeling Strategic Data Modeling Many organizations select IS development projects based on strategic plans. Includes vision and architecture for information systems Identifies and prioritizes develop projects Includes enterprise data model as starting point for projects Data Modeling during Systems Analysis Data model for a single information system is called an application data model. Context data model includes only entities and general entity relationships.
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Logical Model Development Stages Iterative process during which more detail is added to the model in each stage: 1. Context Data model To establish project scope 2. Key-base data model Eliminate nonspecific relationships Add associative entities Include primary and alternate keys Precise cardinalities 3. Fully attributed data model All remaining attributes Subsetting criteria 4. Normalized data model
Background image of page 4
Data Modeling Concepts: Entity Entity – a class of persons, places, objects, events, or concepts about which we need to capture and store data. Named by a singular noun Entity instance a single occurrence of an entity. Student ID Last Name First Name 2144 Arnold Betty 3122 Taylor John 3843 Simmons Lisa 9844 Macy Bill 2837 Leath Heather 2293 Wrench Tim entity instance
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Data Modeling Concepts: Attributes Attribute – a descriptive property or characteristic of an entity. Synonyms include element , and field . Just as a physical student can have attributes, such as hair color, height, etc., a data entity has data attributes Compound attribute – an attribute that consists of other attributes. Synonyms in different data modeling languages are numerous: concatenated attribute, composite attribute, and data structure.
Background image of page 6
Data Modeling Concepts: Data Type identifies what type of data can be stored in that attribute. Representative Logical Data Types for Attributes Logical Data Type Logical Business Meaning NUMBER Any number, real or integer. TEXT A string of characters, inclusive of numbers. When numbers are included in a TEXT attribute, it means that we do not expect to perform arithmetic or comparisons with those numbers. MEMO Same as TEXT but of an indeterminate size. Some business systems require the ability to attach potentially lengthy notes to a give database record.
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 8
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 10/22/2010 for the course ISOM 313 taught by Professor Mee during the Fall '10 term at Suffolk.

Page1 / 35

chap008 (1) - Context Diagram Use Case Development Data...

This preview shows document pages 1 - 8. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online