1. A computer implemented method of enabling a user to search for data items of interest in a database system, said method comprising: storing a plurality of data items in said database system according to a plurality of relationships, said plurality of data items representing a plurality of entity instances, each of said plurality of entity instances being one of a plurality of entity types, each relationship specifying an entity type as a primary entity and another entity type as a secondary entity; displaying a first set of entity types on a display unit, wherein said first set of entity types is contained in said plurality of entity types; receiving a first selection from said user, said first selection indicating a first entity type contained in said first set of entity types; identifying, in response to said receiving of said first entity type as said first selection, a second set of entity types contained in said plurality of entity types, wherein each of said second set of entity types is related as a respective secondary entity to said first entity type according to said plurality of relationships; and enabling said user to request a search on a combination of said first entity type and at least one of said second set of entity types to determine a set of entity instances of interest contained in said plurality of entity instances, wherein said user is enabled to request said search after said identifying.