ACC2000: Adding a Parameter to a Union Query

An easy way to prompt a user for a search criteria in a query is to create a parameter query. However, to use a parameter in a union query, you must follow some specific rules. This article uses the Customers and Suppliers By City query in the sample database Northwind.mdb to describe how to add a parameter to a union query.

The Customers and Suppliers By City union query selects records from both the Customers and Suppliers tables. The SQL of this query is as follows: To add a parameter to the union query, you must duplicate the parameter in each SELECT clause in the query. To add a parameter (in this case a city) to the query, follow these steps.

CAUTION: If you follow the steps in this example, you modify the sample database Northwind.mdb. You may want to back up the Northwind.mdb file and follow these steps on a copy of the database.

1. Open the sample database Northwind.mdb.
2. Open the Customers and Suppliers By City query in Design view.
3. Change the query's SQL so that it looks like the following:

   SELECT City, CompanyName, ContactName, "Customers" AS [Relationship]
   FROM Customers
   WHERE Country = "Brazil" and City = [Enter City]
   UNION SELECT City, CompanyName, ContactName, "Suppliers"
   FROM Suppliers
   WHERE Country = "Brazil" and City = [Enter City]
   ORDER BY City, CompanyName;
   					

4. Save the query and close it.
5. Open the query in Datasheet view and type Rio de Janeiro in the Enter City dialog box. Note that only the Customers and Suppliers from Rio de Janeiro are displayed.

For more information about union queries, click Microsoft Access Help on the Help menu, type union queries in the Office Assistant or the Answer Wizard, and then click Search to view the topics returned.