1. A computer-implemented method of providing access to physical data in a physical database, comprising: (i) providing a physical data field layer that includes a plurality of physical data fields, wherein each physical data field specifies a mapping from the physical data field to a data location in the physical database; and (ii) providing a logical field layer that includes a plurality of logical field definitions, each of the definitions comprising a logical field name and a reference to an access method that defines a manner of exposing specified data for the logical field definition.