1. A computer-readable storage medium containing a program which, when executed by a processor, performs a process of constructing queries selectively capable of returning aggregation information related to data in a database, the process comprising: in response to input specifying attributes for an abstract query, generating an object containing entities including at least one result criterion, selection criteria, an aggregation operation and aggregation logic associating the aggregation operation with the at least one result criterion; wherein the at least one result criterion for the abstract query comprises one or more logical fields, each corresponding to a logical field specification of a data abstraction model abstractly describing the data in the database, each result criterion corresponding to a respective one of the one or more logical fields for which data is to be returned; and wherein the aggregation operation is to be performed with respect to the at least one result criterion for generating aggregation information; and accessing the object to selectively (i) generate a first executable query corresponding to the abstract query inclusive of the aggregation operation and aggregation logic; and (ii) generate a second executable query corresponding to the abstract query exclusive of the aggregation operation and aggregation logic.