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

NAME

       CREATE VIEW - define a new view

SYNOPSIS

       CREATE [ OR REPLACE ] VIEW view [ ( column name list ) ] AS SELECT query

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

       column name list
	      An optional list of names to be used for columns of the view.  If given, these names override the column names that would be deduced
	      from the SQL query.

       query  An SQL 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 arguments.

   OUTPUTS
       CREATE VIEW
	      The message returned if the view is successfully created.

       ERROR: Relation 'view' already exists
	      This error occurs if the view specified already exists in the database.

       WARNING: Attribute 'column' has an unknown type
	      The view will be created having a column with an unknown type if you do not specify it. For example, the following command  gives  a
	      warning:

	      CREATE VIEW vista AS SELECT 'Hello World'

	      whereas this command does not:

	      CREATE VIEW vista AS SELECT text 'Hello World'

DESCRIPTION

       CREATE VIEW defines a view of a query.  The view is not physically materialized. Instead, a query rewrite rule (an ON SELECT rule) is auto-
       matically generated to support SELECT operations on views.

       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 one at the front of the search path; see CURRENT_SCHEMA()).  The view name must  be  distinct  from  the
       name of any other view, table, sequence, or index in the same schema.

   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.

USAGE

       Create a view consisting of all Comedy films:

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

       SELECT * FROM kinds;

	code  | 	  title 	  | did | date_prod  |	kind  | len
       -------+---------------------------+-----+------------+--------+-------
	UA502 | Bananas 		  | 105 | 1971-07-13 | Comedy | 01:22
	C_701 | There's a Girl in my Soup | 107 | 1970-06-11 | Comedy | 01:36
       (2 rows)

COMPATIBILITY

   SQL92
       SQL92 specifies some additional capabilities for the CREATE VIEW statement:

       CREATE VIEW view [ column [, ...] ]
	   AS SELECT expression [ AS colname ] [, ...]
	   FROM table [ WHERE condition ]
	   [ WITH [ CASCADE | LOCAL ] CHECK OPTION ]

       The optional clauses for the full SQL92 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 satisfy the
	      view-defining condition. 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					    2002-11-22							    CREATE VIEW(7)