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[SPARK-28798][DOC][SQL] Document DROP TABLE/VIEW statement in SQL Reference

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### What changes were proposed in this pull request?
Added doc for DROP TABLE and DROP VIEW sql command

### Why are the changes needed?
For reference DROP TABLE  or DROP VIEW in spark-sql

### Does this PR introduce any user-facing change?
It updates DROP TABLE  or DROP VIEW reference doc

### How was this patch tested?
<details>
<summary> Attached the Snap</summary>

DROP TABLE

![image](https://user-images.githubusercontent.com/7912929/67884038-2443b400-fb6b-11e9-9773-b21dae398789.png)
![image](https://user-images.githubusercontent.com/7912929/67797387-aa96c200-faa7-11e9-90d4-fa8b7c6a4ec7.png)

DROP VIEW
![image](https://user-images.githubusercontent.com/7912929/67797463-c306dc80-faa7-11e9-96ec-e2f2e89d0db8.png)
![image](https://user-images.githubusercontent.com/7912929/67797648-1ed16580-faa8-11e9-9d32-19106326e3d9.png)

</details>

Closes #25533 from shivusondur/jiraUSEDB.

Authored-by: shivusondur <shivusondur@gmail.com>
Signed-off-by: Sean Owen <sean.owen@databricks.com>
This commit is contained in:
shivusondur 2019-11-04 11:52:19 -06:00 committed by Sean Owen
parent e524a3a223
commit f29a979e42
2 changed files with 126 additions and 2 deletions
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67
docs/sql-ref-syntax-ddl-drop-table.md
View file

@ -19,4 +19,69 @@ license: |
limitations under the License.
---
**This page is under construction**
### Description
`DROP TABLE` deletes the table and removes the directory associated with the table from the file system
if the table is not `EXTERNAL` table. If the table is not present it throws an exception.
In case of an external table, only the associated metadata information is removed from the metastore database.
### Syntax
{% highlight sql %}
DROP TABLE [IF EXISTS] [database_name.]table_name
{% endhighlight %}
### Parameter
<dl>
<dt><code><em>IF EXISTS</em></code></dt>
<dd>
If specified, no exception is thrown when the table does not exists.
</dd>
<dt><code><em>database_name</em></code></dt>
<dd>
Specifies the database name where table is present.
</dd>
<dt><code><em>table_name</em></code></dt>
<dd>
Specifies the table name to be dropped.
</dd>
</dl>
### Example
{% highlight sql %}
-- Assumes a table named `employeetable` exists.
DROP TABLE employeetable;
+---------+--+
| Result |
+---------+--+
+---------+--+
-- Assumes a table named `employeetable` exists in the `userdb` database
DROP TABLE userdb.employeetable;
+---------+--+
| Result |
+---------+--+
+---------+--+
-- Assumes a table named `employeetable` does not exists.
-- Throws exception
DROP TABLE employeetable;
Error: org.apache.spark.sql.AnalysisException: Table or view not found: employeetable;
(state=,code=0)
-- Assumes a table named `employeetable` does not exists,Try with IF EXISTS
-- this time it will not throw exception
DROP TABLE IF EXISTS employeetable;
+---------+--+
| Result |
+---------+--+
+---------+--+
{% endhighlight %}
### Related Statements
- [CREATE TABLE](sql-ref-syntax-ddl-create-table.html)
- [CREATE DATABASE](sql-ref-syntax-ddl-create-database.html)
- [DROP DATABASE](sql-ref-syntax-ddl-drop-database.html)

61
docs/sql-ref-syntax-ddl-drop-view.md
View file

@ -19,4 +19,63 @@ license: |
limitations under the License.
---
**This page is under construction**
### Description
`DROP VIEW` removes the metadata associated with a specified view from the catalog.
### Syntax
{% highlight sql %}
DROP VIEW [IF EXISTS] [database_name.]view_name
{% endhighlight %}
### Parameter
<dl>
<dt><code><em>IF EXISTS</em></code></dt>
<dd>
If specified, no exception is thrown when the view does not exists.
</dd>
<dt><code><em>database_name</em></code></dt>
<dd>
Specifies the database name where view is present.
</dd>
<dt><code><em>view_name</em></code></dt>
<dd>
Specifies the view name to be dropped.
</dd>
</dl>
### 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 %}
### Related Statements
- [CREATE VIEW](sql-ref-syntax-ddl-create-view.html)
- [CREATE DATABASE](sql-ref-syntax-ddl-create-database.html)
- [DROP DATABASE](sql-ref-syntax-ddl-drop-database.html)