Relationships in the Physical Model
A relationship is used in a physical model to show that there is an association or link between two tables, or between a table and itself. You can use the physical modeling features to add the following relationships:
- Identifying relationships
- Non-identifying relationships
- Recursive relationships
In the diagram window, each relationship can visually depict the following information:
- Type of relationship
- Parent end of relationship
- Child end of relationship
- Optional symbol (only for non-identifying relationships)
- Referential integrity
- Foreign key name
- Cardinality
Relationships also display in the Model Explorer. You can add, review, and modify relationships using the Model Explorer.
Hovering the mouse over a relationship highlights the involved primary and foreign keys.
Relationships are used in both the logical and physical models, and can be represented in either model as one or more foreign key attributes.
There are several ways to add relationships:
- Using the relationship tools
- Reverse engineering an existing database
- Using the Model Explorer
When you add a relationship, the relationship is labeled R_n, where R stands for relationship, and n is a unique number. A number is assigned only once per model and new relationship numbers are calculated beginning with the number zero.
You can click a relationship line to highlight it. Highlighting allows you to trace the path of the relationship line from parent to child.
|
Copyright © 2019 erwin, Inc.
All rights reserved.
|
|