179289f0bf
### What changes were proposed in this pull request?
This PR intends to clean up the SQL documents in `doc/sql-ref*`.
Main changes are as follows;
- Fixes wrong syntaxes and capitalize sub-titles
- Adds some DDL queries in `Examples` so that users can run examples there
- Makes query output in `Examples` follows the `Dataset.showString` (right-aligned) format
- Adds/Removes spaces, Indents, or blank lines to follow the format below;
```
---
license...
---
### Description
Writes what's the syntax is.
### Syntax
{% highlight sql %}
SELECT...
WHERE... // 4 indents after the second line
...
{% endhighlight %}
### Parameters
<dl>
<dt><code><em>Param Name</em></code></dt>
<dd>
Param Description
</dd>
...
</dl>
### Examples
{% highlight sql %}
-- It is better that users are able to execute example queries here.
-- So, we prepare test data in the first section if possible.
CREATE TABLE t (key STRING, value DOUBLE);
INSERT INTO t VALUES
('a', 1.0), ('a', 2.0), ('b', 3.0), ('c', 4.0);
-- query output has 2 indents and it follows the `Dataset.showString`
-- format (right-aligned).
SELECT * FROM t;
+---+-----+
|key|value|
+---+-----+
| a| 1.0|
| a| 2.0|
| b| 3.0|
| c| 4.0|
+---+-----+
-- Query statements after the second line have 4 indents.
SELECT key, SUM(value)
FROM t
GROUP BY key;
+---+----------+
|key|sum(value)|
+---+----------+
| c| 4.0|
| b| 3.0|
| a| 3.0|
+---+----------+
...
{% endhighlight %}
### Related Statements
* [XXX](xxx.html)
* ...
```
### Why are the changes needed?
The most changes of this PR are pretty minor, but I think the consistent formats/rules to write documents are important for long-term maintenance in our community
### Does this PR introduce any user-facing change?
Yes.
### How was this patch tested?
Manually checked.
Closes #28151 from maropu/MakeRightAligned.
Authored-by: Takeshi Yamamuro <yamamuro@apache.org>
Signed-off-by: Sean Owen <srowen@gmail.com>
9 KiB
| layout | title | displayTitle | license |
|---|---|---|---|
| global | ALTER VIEW | ALTER 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
The ALTER VIEW statement can alter metadata associated with the view. It can change the definition of the view, change
the name of a view to a different name, set and unset the metadata of the view by setting TBLPROPERTIES.
RENAME View
Renames the existing view. If the new view name already exists in the source database, a TableAlreadyExistsException is thrown. This operation
does not support moving the views across databases.
Syntax
{% highlight sql %} ALTER VIEW view_identifier RENAME TO view_identifier {% endhighlight %}
Parameters
view_identifier-
Specifies a view name, which may be optionally qualified with a database name.
Syntax:[ database_name. ] view_name
SET View Properties
Set one or more properties of an existing view. The properties are the key value pairs. If the properties' keys exist, the values are replaced with the new values. If the properties' keys do not exist, the key value pairs are added into the properties.
Syntax
{% highlight sql %} ALTER VIEW view_identifier SET TBLPROPERTIES ( property_key = property_val [ , ... ] ) {% endhighlight %}
Parameters
view_identifier-
Specifies a view name, which may be optionally qualified with a database name.
Syntax:[ database_name. ] view_name property_key-
Specifies the property key. The key may consists of multiple parts separated by dot.
Syntax:[ key_part1 ] [ .key_part2 ] [ ... ]
UNSET View Properties
Drop one or more properties of an existing view. If the specified keys do not exist, an exception is thrown. Use
IF EXISTS to avoid the exception.
Syntax
{% highlight sql %} ALTER VIEW view_identifier UNSET TBLPROPERTIES [ IF EXISTS ] ( property_key [ , ... ] ) {% endhighlight %}
Parameters
view_identifier-
Specifies a view name, which may be optionally qualified with a database name.
Syntax:[ database_name. ] view_name property_key-
Specifies the property key. The key may consists of multiple parts separated by dot.
Syntax:[ key_part1 ] [ .key_part2 ] [ ... ]
ALTER View AS SELECT
ALTER VIEW view_identifier AS SELECT statement changes the definition of a view, the SELECT statement must be valid,
and the view_identifier must exist.
Syntax
{% highlight sql %} ALTER VIEW view_identifier AS select_statement {% endhighlight %}
Note that ALTER VIEW statement does not support SET SERDE or SET SERDEPROPERTIES properties.
Parameters
view_identifier-
Specifies a view name, which may be optionally qualified with a database name.
Syntax:[ database_name. ] view_name select_statement- Specifies the definition of the view, detail check select_statement
Examples
{% highlight sql %}
-- Rename only changes the view name.
-- The source and target databases of the view have to be the same.
-- Use qualified or unqualified name for the source and target view
ALTER VIEW tempdb1.v1 RENAME TO tempdb1.v2;
-- Verify that the new view is created. DESCRIBE TABLE EXTENDED tempdb1.v2; +----------------------------+----------+-------+ | col_name|data_type |comment| +----------------------------+----------+-------+ | c1| int| null| | c2| string| null| | | | | |# Detailed Table Information| | | | Database| tempdb1| | | Table| v2| | +----------------------------+----------+-------+
-- Before ALTER VIEW SET TBLPROPERTIES DESC TABLE EXTENDED tempdb1.v2; +----------------------------+----------+-------+ | col_name| data_type|comment| +----------------------------+----------+-------+ | c1| int| null| | c2| string| null| | | | | |# Detailed Table Information| | | | Database| tempdb1| | | Table| v2| | | Table Properties| [....]| | +----------------------------+----------+-------+
-- Set properties in TBLPROPERTIES ALTER VIEW tempdb1.v2 SET TBLPROPERTIES ('created.by.user' = "John", 'created.date' = '01-01-2001' );
-- Use DESCRIBE TABLE EXTENDED tempdb1.v2 to verify
DESC TABLE EXTENDED tempdb1.v2;
+----------------------------+-----------------------------------------------------+-------+
| col_name| data_type|comment|
+----------------------------+-----------------------------------------------------+-------+
| c1| int| null|
| c2| string| null|
| | | |
|# Detailed Table Information| | |
| Database| tempdb1| |
| Table| v2| |
| Table Properties|[created.by.user=John, created.date=01-01-2001, ....]| |
+----------------------------+-----------------------------------------------------+-------+
-- Remove the key created.by.user and created.date from TBLPROPERTIES
ALTER VIEW tempdb1.v2 UNSET TBLPROPERTIES ('created.by.user', 'created.date');
--Use DESC TABLE EXTENDED tempdb1.v2 to verify the changes
DESC TABLE EXTENDED tempdb1.v2;
+----------------------------+----------+-------+
| col_name| data_type|comment|
+----------------------------+----------+-------+
| c1| int| null|
| c2| string| null|
| | | |
|# Detailed Table Information| | |
| Database| tempdb1| |
| Table| v2| |
| Table Properties| [....]| |
+----------------------------+----------+-------+
-- Change the view definition ALTER VIEW tempdb1.v2 AS SELECT * FROM tempdb1.v1;
-- Use DESC TABLE EXTENDED to verify
DESC TABLE EXTENDED tempdb1.v2;
+----------------------------+---------------------------+-------+
| col_name| data_type|comment|
+----------------------------+---------------------------+-------+
| c1| int| null|
| c2| string| null|
| | | |
|# Detailed Table Information| | |
| Database| tempdb1| |
| Table| v2| |
| Type| VIEW| |
| View Text| select * from tempdb1.v1| |
| View Original Text| select * from tempdb1.v1| |
+----------------------------+---------------------------+-------+
{% endhighlight %}