CREATE_VIEW man page on Alpinelinux

Man page or keyword search:  
man Server   18016 pages
apropos Keyword Search (all sections)
Output format
Alpinelinux logo
[printable version]

CREATE VIEW(7)		PostgreSQL 9.3.4 Documentation		CREATE VIEW(7)

NAME
       CREATE_VIEW - define a new view

SYNOPSIS
       CREATE [ OR REPLACE ] [ TEMP | TEMPORARY ] [ RECURSIVE ] VIEW name [ ( column_name [, ...] ) ]
	   [ WITH ( view_option_name [= view_option_value] [, ... ] ) ]
	   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
       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, index or foreign table 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).

       RECURSIVE
	   Creates a recursive view. The syntax

	       CREATE RECURSIVE VIEW name (columns) AS SELECT ...;

	   is equivalent to

	       CREATE VIEW name AS WITH RECURSIVE name (columns) AS (SELECT ...) SELECT columns FROM name;

	   A view column list must be specified for a recursive view.

       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.

       WITH ( view_option_name [= view_option_value] [, ... ] )
	   This clause specifies optional parameters for a view; currently,
	   the only supported parameter name is security_barrier, which should
	   be enabled when a view is intended to provide row-level security.
	   See Section 38.5, “Rules and Privileges”, in the documentation for
	   full details.

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

NOTES
       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 Section 38.5, “Rules and Privileges”, 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).

   Updatable Views
       Simple views are automatically updatable: the system will allow INSERT,
       UPDATE and DELETE statements to be used on the view in the same way as
       on a regular table. A view is automatically updatable if it satisfies
       all of the following conditions:

       ·   The view must have exactly one entry in its FROM list, which must
	   be a table or another updatable view.

       ·   The view definition must not contain WITH, DISTINCT, GROUP BY,
	   HAVING, LIMIT, or OFFSET clauses at the top level.

       ·   The view definition must not contain set operations (UNION,
	   INTERSECT or EXCEPT) at the top level.

       ·   All columns in the view's select list must be simple references to
	   columns of the underlying relation. They cannot be expressions,
	   literals or functions. System columns cannot be referenced, either.

       ·   No column of the underlying relation can appear more than once in
	   the view's select list.

       ·   The view must not have the security_barrier property.

       If the view is automatically updatable the system will convert any
       INSERT, UPDATE or DELETE statement on the view into the corresponding
       statement on the underlying base relation.

       If an automatically updatable view contains a WHERE condition, the
       condition restricts which rows of the base relation are available to be
       modified by UPDATE and DELETE statements on the view. However, an
       UPDATE is allowed to change a row so that it no longer satisfies the
       WHERE condition, and thus is no longer visible through the view.
       Similarly, an INSERT command can potentially insert base-relation rows
       that do not satisfy the WHERE condition and thus are not visible
       through the view.

       A more complex view that does not satisfy all these conditions is
       read-only by default: the system will not allow an insert, update, or
       delete on the view. You can get the effect of an updatable view by
       creating INSTEAD OF triggers on the view, which must convert attempted
       inserts, etc. on the view into appropriate actions on other tables. For
       more information see CREATE TRIGGER (CREATE_TRIGGER(7)). Another
       possibility is to create rules (see CREATE RULE (CREATE_RULE(7))), but
       in practice triggers are easier to understand and use correctly.

       Note that the user performing the insert, update or delete on the view
       must have the corresponding insert, update or delete privilege on the
       view. In addition the view's owner must have the relevant privileges on
       the underlying base relations, but the user performing the update does
       not need any permissions on the underlying base relations (see Section
       38.5, “Rules and Privileges”, in the documentation).

EXAMPLES
       Create a view consisting of all comedy films:

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

       This will create a view containing the columns that are in the film
       table at the time of view creation. Though * was used to create the
       view, columns added later to the table will not be part of the view.

       Create a recursive view consisting of the numbers from 1 to 100:

	   CREATE RECURSIVE VIEW nums_1_100 (n) AS
	       VALUES (1)
	   UNION ALL
	       SELECT n+1 FROM nums_1_100 WHERE n < 100;

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 controls the behavior of automatically updatable views.
	   When given, INSERT and UPDATE commands on the view will be checked
	   to ensure new rows satisfy the view-defining condition (that is,
	   the new rows would be visible through the view). If they do not,
	   the update will be rejected. Without CHECK OPTION, INSERT and
	   UPDATE commands on the view are allowed to create rows that are not
	   visible through the view. (The latter behavior is the only one
	   currently provided by PostgreSQL.)

       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. The WITH clause is an extension as well.

SEE ALSO
       ALTER VIEW (ALTER_VIEW(7)), DROP VIEW (DROP_VIEW(7)), CREATE
       MATERIALIZED VIEW (CREATE_MATERIALIZED_VIEW(7))

PostgreSQL 9.3.4		     2014			CREATE VIEW(7)
[top]

List of man pages available for Alpinelinux

Copyright (c) for man pages and the logo by the respective OS vendor.

For those who want to learn more, the polarhome community provides shell access and support.

[legal] [privacy] [GNU] [policy] [cookies] [netiquette] [sponsors] [FAQ]
Tweet
Polarhome, production since 1999.
Member of Polarhome portal.
Based on Fawad Halim's script.
....................................................................
Vote for polarhome
Free Shell Accounts :: the biggest list on the net