1. A computer-readable storage medium containing a program which, when executed by a processor, performs operations causing modification of physical data comprising a plurality of physical entities and having a particular physical data representation in a database, the operations causing modification of physical data comprising: generating a single abstract modification specification abstractly defining modification operations to modify the physical data, wherein the abstract modification specification comprises a respective logical value for a plurality of logical fields corresponding to physical entities of the database; transforming the abstract modification specification into at least two physical modification statements consistent with the particular physical data representation according to logical field definitions for each of the plurality of logical fields, wherein: each logical field definition includes a logical field name and a reference to at least one access method, the at least one access method is configured to associate the logical field name to the particular physical data representation, the at least one access method is selected from at least two different types of access methods, and each of the at least two physical modification statements modifies a different physical entity of the physical data; ordering the at least two physical modification statements; and executing the modification operations according to the physical modification statements, whereby the physical data is modified.