CREATE VIEW(7) SQL Commands CREATE VIEW(7)
CREATE VIEW - define a new view
CREATE [ OR REPLACE ] VIEW view [ ( column name list ) ] AS SELECT query
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.
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'
CREATE VIEW defines a view of a query. The view is not physically materialized. Instead,
a query rewrite rule (an ON SELECT rule) is automatically 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.
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.
Create a view consisting of all Comedy films:
CREATE VIEW kinds AS
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
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:
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.
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)