a75dc80a76
### What changes were proposed in this pull request? Remove the unneeded embedded inline HTML markup by using the basic markdown syntax. Please see #28414 ### Why are the changes needed? Make the doc cleaner and easily editable by MD editors. ### Does this PR introduce _any_ user-facing change? No ### How was this patch tested? Manually build and check Closes #28451 from huaxingao/html_cleanup. Authored-by: Huaxin Gao <huaxing@us.ibm.com> Signed-off-by: Sean Owen <srowen@gmail.com>
90 lines
3 KiB
Markdown
90 lines
3 KiB
Markdown
---
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layout: global
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title: CREATE VIEW
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displayTitle: CREATE VIEW
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license: |
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Licensed to the Apache Software Foundation (ASF) under one or more
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contributor license agreements. See the NOTICE file distributed with
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this work for additional information regarding copyright ownership.
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The ASF licenses this file to You under the Apache License, Version 2.0
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(the "License"); you may not use this file except in compliance with
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the License. You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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---
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### Description
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Views are based on the result-set of an `SQL` query. `CREATE VIEW` constructs
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a virtual table that has no physical data therefore other operations like
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`ALTER VIEW` and `DROP VIEW` only change metadata.
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### Syntax
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```sql
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CREATE [ OR REPLACE ] [ [ GLOBAL ] TEMPORARY ] VIEW [ IF NOT EXISTS ] view_identifier
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create_view_clauses AS query
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```
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### Parameters
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* **OR REPLACE**
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If a view of same name already exists, it will be replaced.
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* **[ GLOBAL ] TEMPORARY**
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TEMPORARY views are session-scoped and will be dropped when session ends
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because it skips persisting the definition in the underlying metastore, if any.
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GLOBAL TEMPORARY views are tied to a system preserved temporary database `global_temp`.
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* **IF NOT EXISTS**
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Creates a view if it does not exist.
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* **view_identifier**
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Specifies a view name, which may be optionally qualified with a database name.
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**Syntax:** `[ database_name. ] view_name`
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* **create_view_clauses**
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These clauses are optional and order insensitive. It can be of following formats.
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* `[ ( column_name [ COMMENT column_comment ], ... ) ]` to specify column-level comments.
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* `[ COMMENT view_comment ]` to specify view-level comments.
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* `[ TBLPROPERTIES ( property_name = property_value [ , ... ] ) ]` to add metadata key-value pairs.
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* **query**
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A [SELECT](sql-ref-syntax-qry-select.html) statement that constructs the view from base tables or other views.
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### Examples
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```sql
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-- Create or replace view for `experienced_employee` with comments.
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CREATE OR REPLACE VIEW experienced_employee
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(ID COMMENT 'Unique identification number', Name)
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COMMENT 'View for experienced employees'
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AS SELECT id, name FROM all_employee
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WHERE working_years > 5;
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-- Create a global temporary view `subscribed_movies` if it does not exist.
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CREATE GLOBAL TEMPORARY VIEW IF NOT EXISTS subscribed_movies
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AS SELECT mo.member_id, mb.full_name, mo.movie_title
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FROM movies AS mo INNER JOIN members AS mb
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ON mo.member_id = mb.id;
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```
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### Related Statements
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* [ALTER VIEW](sql-ref-syntax-ddl-alter-view.html)
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* [DROP VIEW](sql-ref-syntax-ddl-drop-view.html)
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* [SHOW VIEWS](sql-ref-syntax-aux-show-views.html)
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