SQL - Structured Query Language

SQL View



View is a Virtual Table that defined by a query. View consists of a set of named columns and rows of data. Yet, a view does not exist as a stored set of data values in a database. The rows and columns of data come from tables referenced in the query defining the view and are produced dynamically when the view is referenced or executed.

The query that defines the view can be from one or more tables or from other views in the current or other databases. Distributed queries can be used to define views that use data from multiple heterogeneous database sources that helps to combine similarly structured data from different servers each of which stores data for a different region of organization.

View can be created only in the current database.
View can reference a maximum of 1,024 columns.
View name stores in sysobjects table in master database.
View columns stores in syscolumns table in master database.
View comment stores in syscomments table in master database.
View dependencies stores in sysdepends table in master database.

If a view depends on a table or view that was dropped, SQL Server occur an error message if anyone execute view. If a new table or view is created, and the table structure does not change from the previous base table, to replace the one dropped, the view again becomes usable. If the new table or view structured changes, then the view must be dropped and recreated.

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