CREATE VIEW#
Примечание
Ниже приведена оригинальная документация Trino. Скоро мы ее переведем на русский язык и дополним полезными примерами.
Синтаксис#
CREATE [ OR REPLACE ] VIEW view_name
[ COMMENT view_comment ]
[ SECURITY { DEFINER | INVOKER } ]
AS query
Описание#
Create a new view of a SELECT query. The view is a logical table that can be referenced by future queries. Views do not contain any data. Instead, the query stored by the view is executed every time the view is referenced by another query.
The optional OR REPLACE clause causes the view to be replaced if it
already exists rather than raising an error.
Security#
In the default DEFINER security mode, tables referenced in the view
are accessed using the permissions of the view owner (the creator or
definer of the view) rather than the user executing the query. This
allows providing restricted access to the underlying tables, for which
the user may not be allowed to access directly.
In the INVOKER security mode, tables referenced in the view are accessed
using the permissions of the user executing the query (the invoker of the view).
A view created in this mode is simply a stored query.
Regardless of the security mode, the current_user function will
always return the user executing the query and thus may be used
within views to filter out rows or otherwise restrict access.
Примеры#
Create a simple view test over the orders table:
CREATE VIEW test AS
SELECT orderkey, orderstatus, totalprice / 2 AS half
FROM orders
Create a view test_with_comment with a view comment:
CREATE VIEW test_with_comment
COMMENT 'A view to keep track of orders.'
AS
SELECT orderkey, orderstatus, totalprice
FROM orders
Create a view orders_by_date that summarizes orders:
CREATE VIEW orders_by_date AS
SELECT orderdate, sum(totalprice) AS price
FROM orders
GROUP BY orderdate
Create a view that replaces an existing view:
CREATE OR REPLACE VIEW test AS
SELECT orderkey, orderstatus, totalprice / 4 AS quarter
FROM orders