View
In a database, a view is the result set of a stored query on the data, which users can query just as they would in a persistent database collection object.
Unlike ordinary base tables in a relational database, a view does not form part of the physical schema, it is a virtual table computed or collated dynamically from data in the database when access to that view is requested. Changes applied to the data in a relevant underlying table are reflected in the data shown in the subsequent invocations of the view.
Advantages
- Represent a subset of data contained in a table. Consequently, limit the degree of exposure of the underlying tables: a given user may have permission to query the view, while denied access to the rest of the base table.
- Join and simplify multiple tables into a single virtual table.
- Act as aggregated tables, where the database engine aggregates data (
SUM,AVERAGE, etc.) and presents calculated results as part of the data. - Hide complexity of data.