Most reports require data to be retrieved from multiple tables. Typically, this involves setting up table relationships between the tables and then creating the appropriate table links for the report. For complex reports, this can be a difficult task.
A virtual table is composed of member tables, member fields, and member keys. A virtual table simplifies gathering data from the member tables, because it contains the information about how the tables are linked together. The fields in the virtual table are selected from the member tables, and typically are a subset of all the fields available in those tables. The keys for the virtual table are selected from the primary table’s keys.
You can’t create virtual tables with the Report Writer. They must be created by the application developer.