ER/Studio - Embarcadero Technologies Product Documentation

USING ER/STUDIO > DEVELOPING THE LOGICAL MODEL
• To modify the properties of a foreign key attribute, you must alter the corresponding primary key column in the
originating parent table.
• To preserve domain consistency, ER/Studio only lets you change the column name of foreign keys. To modify
other properties of a foreign key column, you must alter the corresponding primary key column in the originating
parent table.
Create a Foreign Key/Relationship
Foreign keys are created when you establish relationships between entities. The primary key of the parent object
becomes the foreign key of the child object. Foreign keys are not displayed in the entity boxes in the Data Model
Window when using Filtered IE (No FKs) but are displayed using all other notation types. For more information, see
Working with Relationships.
Specify FK Attribute Name and Datatype
By default, the foreign keys inherit their names from the primary key of the parent object; however, you can choose to
provide another name for the foreign key using the Logical Rolename.
1 Double-click the entity you want to change.
2 Click the foreign key in the attributes list and then click Edit.
3 Enter a Logical Rolename and then select Synchronize Column Rolename with Logical Rolename.
4 Click Save.
The child now displays the logical rolename of the foreign key.
Similarly, you can specify a different datatype for the foreign key.
1 Double-click the entity and from the Entity Editor, select the foreign key from the attributes list and then click
Edit.
2 Select Edit Foreign Key Datatype and then make the necessary changes to the datatype.
3 Click Save.
Working with Relationships
Relationships help enforce business rules and assertions in a data model. Relationships determine how data are
related between two entities and/or views. Relationships are implemented as foreign keys in the physical model. The
properties of these foreign keys dictate how referential integrity is enforced between tables through constraints and
triggers.
In addition to standard relationships ER/Studio lets you create recursive relationships, those where an object is related
to itself; duplicate relationships, where multiple relationships relate to the same objects; view relationships that relate
entities or tables to views, and subtype clusters that associate multiple homogenous entities (subtypes) to a supertype
entity.
For more information on relationships, see the following topics:
• Creating and Editing Relationships
• Creating and Editing Recursive Relationships
• Creating View Relationships
• Creating Subtype Cluster Relationships
EMBARCADERO TECHNOLOGIES > ER/STUDIO® 8.0.3 USER GUIDE 130