You may not use one-to-one relationships very often, but you should know how to create them. You start by creating a one-to-many relationship, and then you change the indexing. Access uses indexing in the same way that you use an index in a book — to find information quickly. When you create a primary key, Access automatically indexes that field, and that makes searches faster.
In a one-to-many relationship, the primary key has indexing turned on, but the foreign key field has indexing turned off. In a one-to-one relationship, both key fields have indexing turned on, and neither field allows duplicate values.
You can use Design View or the ribbon to turn on indexing for your foreign key fields. We’ll show you how to use Design View here, and how to use the ribbon during the practice session.
In the Navigation Pane, right-click the table that contains the foreign key field, then click Design View
In the designer, click the foreign key field.
Under Field Properties
, on the General
tab, click the list next to Indexed
and select Yes (No Duplicates)
Save your changes — and there you go. For more information about indexes and duplicate values, see the links in the Quick Reference Card at the end of this course.