When a user inputs a first extraction condition and a second extraction condition, a first data group is extracted from data registered in a database based on the first extraction condition, and a second data group is extracted from the database based on the second extraction condition. Then, common data that is data that belongs to both the first data group and the second data group is extracted. Finally, information about the common data and other data, which is data in the second data group other than the common data, is displayed in a distinguishable manner.