Databases Illuminated, 4th Edition

15.9 Views and View Materialization

Views play an important role in data warehouses, as they do in operational databases, in customizing the user’s environment. SQL operators, including OLAP operators, can be performed on views as well as on base tables. The SQL CREATE VIEW command simply defines the view and does not create any new tables. When a query is written on a view, one way it can be executed is through query modification, which replaces the reference in the WHERE line by the view definition. For example, we can have a view, BestSalespeople, created from the Salespersons table pictured in Figure 15.4(A) defined by

CREATE VIEW BestSalespeople

AS SELECT S.salespersonId, S.lastName, S.firstName, S.phone, S.totalSalesYTD

FROM Salespersons ...