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 gen-
       erate  the  same columns 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 TEMPO-
              RARY 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. 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  in  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, 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                                  2011-09-22                                             CREATE VIEW(7)