When two tables are in a one-to-many relationship, you can create a Find Unmatched Records query to identify any records in the table on the "one" side that have no corresponding records in the table on the "many" side. For example, in the Northwind sample database, because the Customers and Orders tables are in a one-to-many relationship, you could identify customers that have never placed an order.
Click the Create tab.
Click Query Wizard.
Click Find Unmatched Query Wizard.
Click OK. ...