BMGT 402 Lecture Notes - Lecture 10: Data Definition Language
3 Apr 2017
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Document Summary
A named relation whose tuples are physically stored in a database: views are dynamic. Provides powerful and flexible security mechanism by hiding parts of database from certain users. Permits users to access data in a customized way, so that same data can be seen by different users in different ways at the same time. Can simplify complex operations on base relations: create view. Create view viewname [ (newcolumnname [ ,]) ] [ with [ cascade | local ] check option ] Can assign a name to each column in view. The subselect is known as the defining query. With check option ensures that if a row fails to satisfy. Where clause of the defining query, it is not added to the underlying base table. If list of column names is specified, it must have same number of items as number of columns produced by subselect. If column name is omitted, each column takes name of corresponding column in subselect.
