a28ed86a38
### What changes were proposed in this pull request? Previously, user can issue `SHOW TABLES` to get info of both tables and views. This PR (SPARK-31113) implements `SHOW VIEWS` SQL command similar to HIVE to get views only.(https://cwiki.apache.org/confluence/display/Hive/LanguageManual+DDL#LanguageManualDDL-ShowViews) **Hive** -- Only show view names ``` hive> SHOW VIEWS; OK view_1 view_2 ... ``` **Spark(Hive-Compatible)** -- Only show view names, used in tests and `SparkSQLDriver` for CLI applications ``` SHOW VIEWS IN showdb; view_1 view_2 ... ``` **Spark** -- Show more information database/viewName/isTemporary ``` spark-sql> SHOW VIEWS; userdb view_1 false userdb view_2 false ... ``` ### Why are the changes needed? `SHOW VIEWS` command provides better granularity to only get information of views. ### Does this PR introduce any user-facing change? Add new `SHOW VIEWS` SQL command ### How was this patch tested? Add new test `show-views.sql` and pass existing tests Closes #27897 from Eric5553/ShowViews. Authored-by: Eric Wu <492960551@qq.com> Signed-off-by: Dongjoon Hyun <dongjoon@apache.org>
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| layout | title | displayTitle | license |
|---|---|---|---|
| global | DROP VIEW | DROP VIEW | 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
DROP VIEW removes the metadata associated with a specified view from the catalog.
Syntax
{% highlight sql %} DROP VIEW [ IF EXISTS ] view_identifier {% endhighlight %}
Parameter
IF EXISTS- If specified, no exception is thrown when the view does not exists.
view_identifier-
Specifies the view name to be dropped. The view name may be optionally qualified with a database name.
Syntax:[ database_name. ] view_name
Example
{% highlight sql %}
-- Assumes a view named employeeView exists.
DROP VIEW employeeView;
+---------+--+
| Result |
+---------+--+
+---------+--+
-- Assumes a view named employeeView exists in the userdb database
DROP VIEW userdb.employeeView;
+---------+--+
| Result |
+---------+--+
+---------+--+
-- Assumes a view named employeeView does not exists.
-- Throws exception
DROP VIEW employeeView;
Error: org.apache.spark.sql.AnalysisException: Table or view not found: employeeView;
(state=,code=0)
-- Assumes a view named employeeView does not exists,Try with IF EXISTS
-- this time it will not throw exception
DROP VIEW IF EXISTS employeeView;
+---------+--+
| Result |
+---------+--+
+---------+--+
{% endhighlight %}