Chapter 4 Building Conceptual Data Models
Generation mode defines the physical implementation of an inheritance structure.
In the CDM, the generation mode indicates which entities in an inheritance structure should correspond to tables in the PDM, as follows:
Generation mode |
Generates table(s) corresponding to | Which have the following properties |
|---|---|---|
| Generate parent | Parent entity | Inherits entity attributes of each child entity
Is affected by child entity relationships. Contains reference to any table which has a many-to-one relationship with child entity |
| Generate children
Inherit all attributes |
Each child entity | Inherits all entity attributes of the parent entity |
| Generate children
Inherit only primary attributes |
Each child entity | Inherits only the identifier of the parent entity |
Primary keys for child tables
When you generate a child table, its primary key is the concatenation of the child entity identifier and the parent entity identifier.
| Copyright (C) 2005. Sybase Inc. All rights reserved. |
| |