Important considerations when using a delete query

• Once you delete records using a delete query, you can't undo the operation. Therefore, you should preview the data that the query selected for deletion before you run the query. You can do this by clicking View on the toolbar, and viewing the query in Datasheet view.
• You should maintain backup copies of your data at all times. If you delete the wrong records, you can retrieve them from your backup copies.
• In some cases, running a delete query might delete records in related tables, even if they're not included in the query. This can happen when your query contains only the table that's on the "one" side of a one-to-many relationship, and you've enabled cascading deletes for that relationship. When you delete records from the "one" table, you'll also delete records from the "many" table. 
• When a delete query contains more than one table, such as a query that deletes duplicate records from one of the tables, the queryÆs UniqueRecords property must be set to Yes.