CREATE 
VIEW(7)							   SQL Commands 						    CREATE VIEW(7)

NAME

       CREATE VIEW - define a new view

SYNOPSIS

       CREATE [ OR REPLACE ] [ TEMP | TEMPORARY ] VIEW name [ ( column_name [, ...] ) ]
	   AS query

DESCRIPTION

       CREATE VIEW defines a view of a query. The view is not physically materialized. Instead, the query is run every time the view is referenced
       in a query.

       CREATE OR REPLACE VIEW is similar, but if a view of the same name already exists, it is replaced. The new query must generate the same col-
       umns that were generated by the existing view query (that is, the same column names in the same order and with the same data types), but it
       may add additional columns to the end of the list. The calculations giving rise to the output columns may be completely different.

       If a schema name is given (for example, CREATE VIEW myschema.myview ...) then the view is created in the specified schema. Otherwise it	is
       created	in the current schema. Temporary views exist in a special schema, so a schema name cannot be given when creating a temporary view.
       The name of the view must be distinct from the name of any other view, table, sequence, or index in the same schema.

PARAMETERS

       TEMPORARY or TEMP
	      If specified, the view is created as a temporary view.  Temporary views are automatically dropped at the end of the current session.
	      Existing	permanent relations with the same name are not visible to the current session while the temporary view exists, unless they
	      are referenced with schema-qualified names.

	      If any of the tables referenced by the view are temporary, the view is created as a temporary view (whether TEMPORARY  is  specified
	      or not).

       name   The name (optionally schema-qualified) of a view to be created.

       column_name
	      An optional list of names to be used for columns of the view.  If not given, the column names are deduced from the query.

       query  A SELECT [select(7)] or VALUES [values(7)] command which will provide the columns and rows of the view.

NOTES

       Currently,  views  are  read only: the system will not allow an insert, update, or delete on a view. You can get the effect of an updatable
       view by creating rules that rewrite inserts, etc. on the view into appropriate actions on other tables. For  more  information  see  CREATE
       RULE [create_rule(7)].

       Use the DROP VIEW [drop_view(7)] statement to drop views.

       Be careful that the names and types of the view's columns will be assigned the way you want. For example:

       CREATE VIEW vista AS SELECT 'Hello World';

       is  bad	form in two ways: the column name defaults to ?column?, and the column data type defaults to unknown. If you want a string literal
       in a view's result, use something like:

       CREATE VIEW vista AS SELECT text 'Hello World' AS hello;

       Access to tables referenced in the view is determined by permissions of the view owner. However, functions called in the view  are  treated
       the same as if they had been called directly from the query using the view.  Therefore the user of a view must have permissions to call all
       functions used by the view.

       When CREATE OR REPLACE VIEW is used on an existing view, only the view's defining SELECT rule is changed.  Other view properties, including
       ownership,  permissions,  and  non-SELECT rules, remain unchanged. You must own the view to replace it (this includes being a member of the
       owning role).

EXAMPLES

       Create a view consisting of all comedy films:

       CREATE VIEW comedies AS
	   SELECT *
	   FROM films
	   WHERE kind = 'Comedy';

COMPATIBILITY

       The SQL standard specifies some additional capabilities for the CREATE VIEW statement:

       CREATE VIEW name [ ( column_name [, ...] ) ]
	   AS query
	   [ WITH [ CASCADED | LOCAL ] CHECK OPTION ]

       The optional clauses for the full SQL command are:

       CHECK OPTION
	      This option has to do with updatable views. All INSERT and UPDATE commands on the view will be checked to ensure	data  satisfy  the
	      view-defining condition (that is, the new data would be visible through the view). If they do not, the update will be rejected.

       LOCAL  Check for integrity on this view.

       CASCADED
	      Check for integrity on this view and on any dependent view. CASCADED is assumed if neither CASCADED nor LOCAL is specified.

       CREATE OR REPLACE VIEW is a PostgreSQL language extension.  So is the concept of a temporary view.

SEE ALSO

       ALTER VIEW [alter_view(7)], DROP VIEW [drop_view(7)]

SQL - Language Statements					    2010-05-14							    CREATE VIEW(7)