Contents
What is a view relation?
A view is a query over one (or more) base relations but does not actually contain any data itself.
Are views always up to date?
They are always up to date. A view is not a persisted object. When you query a view, you are actually querying the underlying tables etc. that make up the view.
What are the advantages of views?
Views can provide advantages over tables:
- Views can represent a subset of the data contained in a table.
- Views can join and simplify multiple tables into a single virtual table.
- Views can act as aggregated tables, where the database engine aggregates data (sum, average, etc.)
- Views can hide the complexity of data.
What is view explain about views?
A view is a subset of a database that is generated from a query and stored as a permanent object. Although the definition of a view is permanent, the data contained therein is dynamic depending on the point in time at which the view is accessed. Views represent a subset of the data contained in a table.
Is a view a relation?
A view (also known as a virtual relation) is a named relation whose value at any given time t is the result of evaluating a certain relational expression at that time t. Here’s an SQL example: Base relations really exist—that is, they’re physically stored in the database.
What is a derived relation?
Definition: A relation between two or more stimuli that is not directly trained and not based on physical properties of the stimuli. If A, B, and C all correspond to the same thing, and only A-B and B-C are directly trained, the relation drawn between A and C is derived.
What is a view and what are the types of views?
System Defined Views will be automatically attached to all User Defined databases. And these provide information about the database, tables, and all the properties of the database and tables. There are three types of System defined views, Information Schema, Catalog View, and Dynamic Management View.