create_view

CREATE VIEW()			 SQL Commands			CREATE VIEW()



NAME
       CREATE VIEW - define a new view


SYNOPSIS
       CREATE [ OR REPLACE ] 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  refer-
       enced in a query.

       CREATE  OR  REPLACE  VIEW  is  similar, but if a view of the same name
       already exists, it is replaced. You can only replace a view with a new
       query  that  generates the identical set of columns (i.e., same column
       names and data types).

       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.  The view name must  be  distinct	 from
       the  name  of  any  other  view, table, sequence, or index in the same
       schema.

PARAMETERS
       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 query (that is, a SELECT statement) which  will	 provide  the
	      columns and rows of the view.

	      Refer  to	 SELECT	 [select(7)] for more information about valid
	      queries.

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 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.

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 [, ...] ) ]
	   AS query
	   [ WITH [ CASCADE | LOCAL ] CHECK OPTION ]


       The optional clauses for the full SQL command are:

       CHECK OPTION
	      This option is to do  with  updatable  views.  All  INSERT  and
	      UPDATE commands on the view will be checked to ensure data sat-
	      isfy 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.

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


       CREATE OR REPLACE VIEW is a PostgreSQL language extension.



SQL - Language Statements	  2008-01-03			CREATE VIEW()