
At the logical level, you specify the information in terms of data structures supported
by a logical data model. For this purpose, we choose the relational data model invented
in 1969 by Dr. E. F. Codd. For example, the residence fact mentioned above might be
stored in a resident Country attribute of a Patient table. Using VEA, you can also dis-
play this information in an ER style notation. At this level, VEA allows you to specify
portable data types that can be mapped to a variety of physical data types depending on
the target database platform. At the physical level, we choose a target database man-
agement system (DBMS) for implementing the logical ...