1. A computer-implemented method of constructing an abstract classification field, comprising: receiving user input specifying a logical field corresponding to a logical field specification of a data abstraction model; receiving user input specifying a classification definition for the logical field; generating the abstract classification field on the basis of the logical field and the classification definition; wherein the data abstraction model describes data in the database independently from a schema of the database, and exposes information as a set of logical fields used to compose abstract queries, wherein the logical field is associated with a specific set of data in the database, and is used to describe the specific set of data, wherein the abstract classification field is associated with the specific set of data in the database and is configured for determining classified information related to the specific set of data, and wherein the classification definition specifies a rule for dividing the specific set of data into a plurality of categories.