2410a45703
### What changes were proposed in this pull request? SQL Reference cleanup ### Why are the changes needed? To complete SQL Reference ### Does this PR introduce _any_ user-facing change? updated sql-ref-syntax-qry.html before <img width="1100" alt="Screen Shot 2020-04-29 at 11 08 25 PM" src="https://user-images.githubusercontent.com/13592258/80677799-70b27280-8a6e-11ea-8e3f-a768f29d0377.png"> after <img width="1100" alt="Screen Shot 2020-04-29 at 11 05 55 PM" src="https://user-images.githubusercontent.com/13592258/80677803-74de9000-8a6e-11ea-880c-aa05c53254a6.png"> ### How was this patch tested? Manually build and check Closes #28417 from huaxingao/cleanup. Authored-by: Huaxin Gao <huaxing@us.ibm.com> Signed-off-by: Takeshi Yamamuro <yamamuro@apache.org>
98 lines
3.5 KiB
Markdown
98 lines
3.5 KiB
Markdown
---
|
|
layout: global
|
|
title: CREATE VIEW
|
|
displayTitle: CREATE VIEW
|
|
license: |
|
|
Licensed to the Apache Software Foundation (ASF) under one or more
|
|
contributor license agreements. See the NOTICE file distributed with
|
|
this work for additional information regarding copyright ownership.
|
|
The ASF licenses this file to You under the Apache License, Version 2.0
|
|
(the "License"); you may not use this file except in compliance with
|
|
the License. You may obtain a copy of the License at
|
|
|
|
http://www.apache.org/licenses/LICENSE-2.0
|
|
|
|
Unless required by applicable law or agreed to in writing, software
|
|
distributed under the License is distributed on an "AS IS" BASIS,
|
|
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
See the License for the specific language governing permissions and
|
|
limitations under the License.
|
|
---
|
|
|
|
### Description
|
|
|
|
Views are based on the result-set of an `SQL` query. `CREATE VIEW` constructs
|
|
a virtual table that has no physical data therefore other operations like
|
|
`ALTER VIEW` and `DROP VIEW` only change metadata.
|
|
|
|
### Syntax
|
|
|
|
{% highlight sql %}
|
|
CREATE [ OR REPLACE ] [ [ GLOBAL ] TEMPORARY ] VIEW [ IF NOT EXISTS ] view_identifier
|
|
create_view_clauses AS query
|
|
{% endhighlight %}
|
|
|
|
### Parameters
|
|
|
|
<dl>
|
|
<dt><code><em>OR REPLACE</em></code></dt>
|
|
<dd>If a view of same name already exists, it will be replaced.</dd>
|
|
</dl>
|
|
<dl>
|
|
<dt><code><em>[ GLOBAL ] TEMPORARY</em></code></dt>
|
|
<dd>TEMPORARY views are session-scoped and will be dropped when session ends
|
|
because it skips persisting the definition in the underlying metastore, if any.
|
|
GLOBAL TEMPORARY views are tied to a system preserved temporary database <code>global_temp</code>.</dd>
|
|
</dl>
|
|
<dl>
|
|
<dt><code><em>IF NOT EXISTS</em></code></dt>
|
|
<dd>Creates a view if it does not exists.</dd>
|
|
</dl>
|
|
<dl>
|
|
<dt><code><em>view_identifier</em></code></dt>
|
|
<dd>
|
|
Specifies a view name, which may be optionally qualified with a database name.<br><br>
|
|
<b> Syntax:</b>
|
|
<code>
|
|
[ database_name. ] view_name
|
|
</code>
|
|
</dd>
|
|
</dl>
|
|
<dl>
|
|
<dt><code><em>create_view_clauses</em></code></dt>
|
|
<dd>These clauses are optional and order insensitive. It can be of following formats.
|
|
<ul>
|
|
<li><code>[ ( column_name [ COMMENT column_comment ], ... ) ]</code> to specify column-level comments.</li>
|
|
<li><code>[ COMMENT view_comment ]</code> to specify view-level comments.</li>
|
|
<li><code>[ TBLPROPERTIES ( property_name = property_value [ , ... ] ) ]</code> to add metadata key-value pairs.</li>
|
|
</ul>
|
|
</dd>
|
|
</dl>
|
|
<dl>
|
|
<dt><code><em>query</em></code></dt>
|
|
<dd>A <a href="sql-ref-syntax-qry-select.html">SELECT</a> statement that constructs the view from base tables or other views.</dd>
|
|
</dl>
|
|
|
|
### Examples
|
|
|
|
{% highlight sql %}
|
|
-- Create or replace view for `experienced_employee` with comments.
|
|
CREATE OR REPLACE VIEW experienced_employee
|
|
(ID COMMENT 'Unique identification number', Name)
|
|
COMMENT 'View for experienced employees'
|
|
AS SELECT id, name FROM all_employee
|
|
WHERE working_years > 5;
|
|
|
|
-- Create a global temporary view `subscribed_movies` if it does not exist.
|
|
CREATE GLOBAL TEMPORARY VIEW IF NOT EXISTS subscribed_movies
|
|
AS SELECT mo.member_id, mb.full_name, mo.movie_title
|
|
FROM movies AS mo INNER JOIN members AS mb
|
|
ON mo.member_id = mb.id;
|
|
{% endhighlight %}
|
|
|
|
### Related Statements
|
|
|
|
* [ALTER VIEW](sql-ref-syntax-ddl-alter-view.html)
|
|
* [DROP VIEW](sql-ref-syntax-ddl-drop-view.html)
|
|
* [SHOW VIEWS](sql-ref-syntax-aux-show-views.html)
|