9. The computer program product of claim 6 , wherein the generating of the second SQL statement for the base table includes transforming one or more predicates of the first SQL statement for the virtual relation into a SQL string to select identifiers of rows of the base table containing values belonging to one or more instances of the virtual relation that satisfy the one or more predicates of the first SQL statement for the virtual relation.
6. A computer program product comprising: a computer readable storage medium having computer readable program code embodied therewith for execution on a processing system, the computer readable program code comprising computer readable program code configured to perform: receiving a first structured query language (SQL) statement including a virtual relation; mapping the virtual relation to a base table of a relational database management system by: referencing a row of a first table of metadata corresponding to the virtual relation and having first information regarding the virtual relation, referencing at least one row of a second table of metadata, each of the at least one row of the second table of metadata including second information regarding to a respective field of at least one field associated with the virtual relation, and referencing at least one row of the base table, each of the at least one row of the base table including an instance of a field value corresponding to the respective field of the at least one field associated with the virtual relation; generating a second SQL statement for the base table from the first SQL statement including the virtual relation by applying the mapping to one or more elements of the first SQL statement for the virtual relation; and applying the second SQL statement against real relations of the base table.