Prevent duplicate records in a query based on fields in the design grid

1. Open a query in Design view.
   
   
2. Select the query by clicking anywhere in query Design view outside the design grid and the field lists.
   
   
3. Click Properties on the toolbar to display the query's property sheet.
   
   
4. Set the UniqueValues property to Yes.

   If the query's results include more than one field, the combination of values from all fields must be unique for a given record to be included in the results.

5. To view the query's results, click View on the toolbar.

Note   When the UniqueValues property is set to Yes, Microsoft Access automatically sets the UniqueRecords property to No.