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CREATE VIEW()			 SQL Commands			 CREATE VIEW()



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 mate-
       rialized. 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. 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.  Temporary  views	 exist	in  a  special
       schema,	so  a  schema  name may not 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.	Tempo-
	      rary 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 speci-
	      fied 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	 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 [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. In some cases, this can be used to provide secure but
       restricted access to the underlying tables. However, not all views  are
       secure  against tampering; see the documentation for details. 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, includ-
       ing 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  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.

       CASCADED
	      Check for integrity on this view and on any dependent view. CAS-
	      CADED 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
       DROP VIEW [drop_view(7)]



SQL - Language Statements	  2010-12-14			 CREATE VIEW()
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