Unique Constraints

Unique constraints enforce the 'uniqueness' of a set of fields in all rows of a Table, this means that no two rows in a Table can have the same values in the fields of an 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 Tools | Database Builder | Click on Table name > Constraints | Right-click | Add New Constraint (Ctrl+N)

In diagram or Project Browser | Right-click on Table | Features & Properties | Operations > Constraint | Add New Constraint (Ctrl+N)

Create a Constraint



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On the 'Constraint' 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.


In the 'Type' field, change the value from 'index' to 'unique'.

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