You can specify certain criteria for the fields of a query to be retrieved from the database via a filter, so that when you build reports on the query, the returned results will be narrowed down. In addition, you can also apply sub-queries to a filter. You can type your filter criteria both in the format of a filter and a QBE (Query By Example). The overall conditions will include them both. Always click the SQL button to view your conditions and parse the query to ensure the syntax is valid.
Notes:
To remove the parameter condition from a query if this happens, check Ignore Predicate If Parameter Value Is Null on the Query menu.