1. A computer-implemented method for logically attributing a field of a source physical table to a target physical table both residing in an underlying physical database, the method being implemented by execution of one or more processors and comprising: providing a database abstraction model defining a plurality of logical fields for composing an abstract query, wherein each logical field specifies (i) a name for the logical field and (ii) an access method that maps the logical field to data in the underlying physical database, wherein at least one of the logical fields is defined as a virtual column of the target physical table different than the source physical table where the data for the at least one logical field physically resides, the logical field defined as the virtual column comprising an access method that maps initially to selected data in the source physical table; receiving an abstract query requesting results for a subset of the plurality of logical fields, excluding the logical field defined as the virtual column, wherein each of a plurality of logical fields defined in the database abstraction model is examined to determine whether the respective logical field is defined as a virtual column, wherein each examined logical field defined as a virtual column that maps to at least some of the same data mapped to by at least one other logical field in the subset is added to the abstract query, thereby generating a modified abstract query that includes the logical field defined as the virtual column by adding the virtual column to the abstract query; for the modified abstract query, creating a first data structure configured to select only the selected data in the source physical table mapped to by the access method of the logical field defined as the virtual column; and for the modified abstract query, changing the access method of the logical field defined as the virtual column to map to the first data structure instead of the source physical table; and wherein the database abstraction model and the first data structure are stored on a storage device.