SQL Server Views

Since a view is a virtual table – columns of the view cannot be renamed. To change anything in the view, the view must be dropped and create again.

The select statement on the view cannot contain ORDER BY or INTO TEMP

When a table or view is dropped, any views in the same database are also dropped.

It is not possible to create an index on a view

It is not possible to use DELETE to update a view that is defined as a join.

An index view has a unique clustered index created on it. They exist as rows on the disk. Because they are saved on the disk, the response time to a query is fast at the cost of space consumption. They are more commonly used in scenarios when data modification is less.

Syntax:

Create Index CREATE [UNIQUE ] [ CLUSTERED | NONCLUSTERED ] INDEX index_name ON table_name

The view is created using the CREATE VIEW synatx

Views can subset data in a table

They can join multiple tables into one virtual table

Views can provide security and decrease complexity

They save space because only their definition is stored.

They can also be used to create abstraction

Materialized views are commonly used in data warehousing. They represent a snapshot of the data from remote sources.

Views can create other calculated fields based on values in the real underlying tables

A view can be considered as a virtual table. It does not physically exist. It is based on the result set of a SQL statement. A view contains rows and tables just like a real table.

Partitioned views allow data in a large table to be split into smaller tables. These small tables are called as member tables. The split is done based on range of data values in one of the columns.

In a distributed portioned view, each member table is on a separate member server. This means that the member tables are distributed. To locate these tables easily, the database name on each server should be same.

In an indexed view, the data is already computed and stored. Data can be accessed by a unique index. This index is a clustered index. In order to create an index the syntax is

CREATE [UNIQUE], [CLUSTERED | NONCLUSTERED] INDEX index_name

ON {view}

[WITH <index_option>]

[ON filegrp]