in the view 34 entitled u201c v computers u201d also have only those columns that appear in the table 28 entitled u201c t computers u201d based on the class 16 entitled u201c computers u201d the records 42 44 46 48 which originate from the view 36 entitled u201c v internet computers u201d thus lack the attribute 24 u201c kb sec u201d in the view 34 u201c v computers u201d since the class 16 entitled u201c computers u201d has no corresponding attribute the structure described allows accessing the records of all instances of the classes 16 18 20 u201c computers u201d u201c internet computers u201d and u201c internet servers u201d for example via a query directed at the view 34 entitled u201c v computers u201d a corresponding sql query regarding all computers having more than 128 mb memory might read u201c select oid class from v computers where ram gt 128 u201d the relational database would return a total of four records 40 44 46 48 as the result of that query the oid and class for each of those records would be returned so that the associated record complete with all attributes i e including those that do not appear listed in the form of columns in the view 34 u201c v computers u201d could be retrieved from the respective tables a corresponding sql query aimed at retrieving all information contained in the record 48 would read u201c select from t internet servers where oid 2 u201d wherein the two items of information on the record 48 class u201c internet servers u201d and oid u201c 2 u201d provided by the first sql query would be utilized fig2 depicts a constellation essentially identical to that of fig1 that.