Setting Referential Integrity Between Existing Tables.
If you have not set Referential Integrity between Tables, the 'links' will appear between Key Fields on the Query window, but there will be no indication as to the actual relationship between records in the Tables (one-to-one, one-to-many, or many-to-many).
To set Referential Integrity on existing Tables, carry out the following steps:
STEP 1 Right-click on the Query window and select Relationships... from the pop-up menu.
STEP 2 Select Edit Relationship... from the pop-up menu
STEP 3 Click in the Enforce Referential Integrity box.
The type of relationship between records will now be indicated in the Relationships window...
When you set up a new Query, the type of relationship will now be indicated in the Query window. In this example, the relationship is indicated as "one-to-one". (Compare the screen below with the first screen on this page.)
