Views can make it easier to create lossless join decomposition.
Without the use of views, the normalization of databases above second normal form would become much more difficult. In another parallel with functions, database users can manipulate nested views, thus one view can aggregate data from other views. Just as a function (in programming) can provide abstraction, so can a database view.
Consequently, a view can limit the degree of exposure of the underlying tables to the outer world: a given user may have permission to query the view, while denied access to the rest of the base table. Views can represent a subset of the data contained in a table.Views can provide advantages over tables: In some NoSQL databases, views are the only way to query data. Changes applied to the data in a relevant underlying table are reflected in the data shown in subsequent invocations of the view. Unlike ordinary base tables in a relational database, a view does not form part of the physical schema: as a result set, it is a virtual table computed or collated dynamically from data in the database when access to that view is requested. This pre-established query command is kept in the database dictionary. In a database, a view is the result set of a stored query on the data, which the database users can query just as they would in a persistent database collection object. JSTOR ( March 2020) ( Learn how and when to remove this template message).Unsourced material may be challenged and removed.
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