Project: Apache Spark (App Definition and Development / Streaming & Messaging)
File: sql-ref-syntax-ddl-create-view.md

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. 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. ```sql CREATE [ OR REPLACE ] [ [ GLOBAL ] TEMPORARY ] VIEW [ IF NOT EXISTS ] view_identifier createviewclauses AS query ``` OR REPLACE* If a view of same name already exists, it will be replaced. [ GLOBAL ] TEMPORARY* 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 `global_temp`. IF NOT EXISTS* Creates a view if it does not exist. view_identifier* Specifies a view name, which may be optionally qualified with a database name. Syntax: `[ databasename. ] viewname` create_view_clauses* These clauses are optional and order insensitive. It can be of following formats. `[ ( columnname [ COMMENT columncomment ], ... ) ]` to specify column-level comments. `[ COMMENT view_comment ]` to specify view-level comments. `[ TBLPROPERTIES ( propertyname = propertyvalue [ , ... ] ) ]` to add metadata key-value pairs. `[ WITH SCHEMA { BINDING | COMPENSATION | [ TYPE ] EVOLUTION } ]` to specify how the view reacts to schema changes This clause is not supported for `TEMPORARY` views. BINDING* - The view can tolerate only type changes in the underlying schema requiring safe up-casts. COMPENSATION* - The view can tolerate type changes in the underlying schema requiring casts. Runtime casting errors may occur. TYPE EVOLUTION* - The view will adapt to any type changes in the underlying schema. EVOLUTION - For views defined without a column lists any schema changes are adapted by the view, including, for queries with `SELECT ` dropped or added columns. If the view is defined with a column list, the clause is interpreted as `TYPE EVOLUTION`. The default is `WITH SCHEMA COMPENSATION`. query* A statement that constructs the view from base tables or other views. ```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.memberid, mb.fullname, mo.movie_title FROM movies AS mo INNER JOIN members AS mb ON mo.member_id = mb.id; -- Create a view filtering the `orders` table which will adjust to schema changes in `orders`. CREATE OR REPLACE VIEW open_orders WITH SCHEMA EVOLUTION AS SELECT * FROM orders WHERE status = 'open'; ```