Chapter 2 Conceptual Data Model Basics
A CDM represents the interaction of the following objects:
| Object | Tool | Description |
|---|---|---|
| Domain | — | Set of values for which a data item is valid |
| Data item | — | Elementary piece of information |
| Entity | 
|
Person, place, thing, or concept that has characteristics of interest to the enterprise and about which you want to store information |
| Entity attribute | — | Elementary piece of information attached to an entity |
| Identifier | — | Entity attribute, or a combination of entity attributes, whose values uniquely identify each occurrence of the entity |
| Relationship | 
|
Named connection or relation between entities (Entity Relationship (ER) modeling methodology) |
| Inheritance | 
|
Special relationship that defines an entity as a special case of a more general entity |
| Association | 
|
Named connection or association between entities (Merise modeling methodology) |
| Association link | 
|
Link that connects an association to an entity and on which you define the cardinality an entity has relative to another |
| Copyright (C) 2005. Sybase Inc. All rights reserved. |
| |