Materialized views, which are derived from base relations and stored in the database, offer opportunities for significant performance gain in query evaluation by providing quick access to the pre-computed data. A materialized view can be utilized in evaluating a query if it has pre-computed result of some part of the query plan. Although many approaches to utilizing materialized views in evaluating a query have been proposed, there exist several restrictions in selecting such views. This paper proposes new ways of utilizing materialized views in answering an aggregate query. Views including relations that are not referred to in the given query are utilized. Attributes missing from a view can be recovered under certain conditions. We identify the conditions where a view may be used in evaluating a query and present the algorithm to search for the most efficient query among the equivalent ones. We also report on a simulation based on the TPC-H and GRID databases. Simulation results show that our approach provides impressive performance improvements to the data warehousing environment where aggregate views are often pre-computed and materialized.