Please note : This help page is not for the latest version of Enterprise Architect. The latest help can be found here.
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Unique Constraints
Unique Constraints enforce the 'uniqueness' of a set of fields in all rows of a Table, which means that no two rows in a Table can have the same values in the fields of a Unique Constraint. Unique Constraints are similar to Primary Keys (in that they also enforce 'uniqueness') but the main difference is that a Table can have multiple Unique Constraints defined but only one Primary Key.
Access
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Ribbon |
Specialize > Tools > Database Builder > Click on Table name > Constraints/Indexes > Right-click > Add New Constraint |
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Context Menu |
In diagram or Project Browser | Right-click on Table element | Features | Constraints/Indexes |
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Keyboard Shortcuts |
Click on Table: > Constraints/Indexes: |
Create a Constraint
Step |
Action |
See also |
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1 |
On the 'Constraints/Indexes' tab, a new constraint is automatically created and assigned the default constraint name and a 'Type' of index. Overtype the constraint name with a name that identifies this as a unique constraint. |
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2 |
In the 'Type' field, change the value from 'index' to 'unique'. |
Notes
- Warning: Enterprise Architect assumes that Unique Constraints have at least one column assigned to them; however, Enterprise Architect does not enforce this rule during modeling
If DDL is generated for a Table that has a unique constraint defined without column(s) assigned, that DDL will be invalid