An element containing a value that you can change to affect the results of the query. For example, a query returning data about an employee might have a parameter for the employee's name. You can then use one QueryDef object to find data about any employee by setting the parameter to a specific name before running the query.
Using the Microsoft� OLE DB Provider for Jet in Microsoft Jet version 4.X, parameters can be exposed from procedures using the ANSI question mark (?) parameter markers. Using SQL syntax, you can create the equivalent to a QueryDef.