CREATE VIEW statement creates a new view, which is a stored query represented as a virtual table.
This statement performs a schema change. For more information about how online schema changes work in CockroachDB, see Online Schema Changes.
The user must have the
CREATE privilege on the parent database and the
SELECT privilege on any table(s) referenced by the view.
||New in v20.1: Create a new view only if a view of the same name does not already exist. If one does exist, do not return an error.
||The name of the view to create, which must be unique within its database and follow these identifier rules. When the parent database is not set as the default, the name must be formatted as
||An optional, comma-separated list of column names for the view. If specified, these names will be used in the response instead of the columns specified in
||The selection query to execute when the view is requested.
Note that it is not currently possible to use
||New in v20.1: Defines the view as a session-scoped temporary view. For more information, see Temporary Views.
Support for temporary views is experimental.
This example highlights one key benefit to using views: simplifying complex queries. For additional benefits and examples, see Views.
Let's say you're using our sample
startrek database, which contains two tables,
quotes. There's a foreign key constraint between the
episodes.id column and the
quotes.episode column. To count the number of famous quotes per season, you could run the following join:
> SELECT startrek.episodes.season, count(*) FROM startrek.quotes JOIN startrek.episodes ON startrek.quotes.episode = startrek.episodes.id GROUP BY startrek.episodes.season;
season | count ---------+-------- 1 | 78 2 | 76 3 | 46 (3 rows)
Alternatively, to make it much easier to run this complex query, you could create a view:
> CREATE VIEW startrek.quotes_per_season (season, quotes) AS SELECT startrek.episodes.season, count(*) FROM startrek.quotes JOIN startrek.episodes ON startrek.quotes.episode = startrek.episodes.id GROUP BY startrek.episodes.season;
The view is then represented as a virtual table alongside other tables in the database:
> SHOW TABLES FROM startrek;
table_name --------------------- episodes quotes quotes_per_season (3 rows)
Executing the query is as easy as
SELECTing from the view, as you would from a standard table:
> SELECT * FROM startrek.quotes_per_season;
season | quotes ---------+--------- 1 | 78 2 | 76 3 | 46 (3 rows)