A technique for appropriately managing a database in an apparatus with a limited storage capacity is described. A client apparatus includes a first storage unit storing part of a record set included in a database of a database server apparatus, and a second storage unit storing a copy of the record set stored in the first storage unit. The client apparatus usually searches the second storage unit. If data is not found, the client apparatus transmits a search request to the database server apparatus and stores a search result in the second storage unit. When the client apparatus receives update data from the database server apparatus, the client apparatus performs processing of updating the first storage unit.