1. A computer-implemented method of constructing abstract classification fields, comprising: receiving user input specifying a logical field corresponding to a logical field specification of a data abstraction model abstractly describing data in a database, the logical field being associated with a specific set of the data; receiving user input specifying a classification definition for the logical field, the classification definition being suitable for dividing the specific set of the data into a plurality of categories; and generating a classification field on the basis of the logical field and the classification definition.