CREATE VIEW - define a new view
CREATE [ OR REPLACE ] [ TEMP | TEMPORARY ] VIEW name [ ( column_name [, ...] ) ] AS query
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. 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.
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).
Refer to SELECT [select(7)] for more information about valid queries.
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. However, 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.
Create a view consisting of all comedy films:
CREATE VIEW comedies AS SELECT * FROM films WHERE kind = 'Comedy';
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:
CREATE OR REPLACE VIEW is a PostgreSQL language extension. So is the concept of a temporary view.
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