CREATE VIEW

Description

Creates a view.

A view, or a logical view, is a virtual table whose data is derived from a query against other existing physical tables. Therefore, a view uses no physical storage, and all queries against the view are equivalent to sub-queries of the query statement used to build the view.

For information about supported materialized views, see Asynchronous materialized views.

CAUTION

Only users with the CREATE VIEW privilege on a specific database can perform this operation.

Syntax

CREATE [OR REPLACE] VIEW [IF NOT EXISTS]
[<database>.]<view_name>
(
    <column_name>[ COMMENT 'column comment']
    [, <column_name>[ COMMENT 'column comment'], ...]
)
[COMMENT 'view comment']
AS <query_statement>

Parameters

Usage notes

• Querying a view requires the SELECT privilege on the view and on its corresponding base tables.
• If the query statement used to build a view cannot be executed due to the Schema Change on the base tables, CelerData returns an error when you query the view.

Examples

Example 1: Create a view named example_view in example_db with an aggregate query against example_table.

CREATE VIEW example_db.example_view (k1, k2, k3, v1)
AS
SELECT c1 as k1, k2, k3, SUM(v1) FROM example_table
WHERE k1 = 20160112 GROUP BY k1,k2,k3;

Example 2: Create a view named example_view in the database example_db with an aggregate query against the table example_table, and specify comments for the view and each column in it.

CREATE VIEW example_db.example_view
(
    k1 COMMENT 'first key',
    k2 COMMENT 'second key',
    k3 COMMENT 'third key',
    v1 COMMENT 'first value'
)
COMMENT 'my first view'
AS
SELECT c1 as k1, k2, k3, SUM(v1) FROM example_table
WHERE k1 = 20160112 GROUP BY k1,k2,k3;

Relevant SQLs

• SHOW CREATE VIEW
• ALTER VIEW
• DROP VIEW