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>
3.5 KiB
| layout | title | displayTitle | license |
|---|---|---|---|
| global | CREATE DATABASE | CREATE DATABASE | 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
Creates a database with the specified name. If database with the same name already exists, an exception will be thrown.
Syntax
{% highlight sql %} CREATE { DATABASE | SCHEMA } [ IF NOT EXISTS ] database_name [ COMMENT database_comment ] [ LOCATION database_directory ] [ WITH DBPROPERTIES ( property_name = property_value [ , ... ] ) ] {% endhighlight %}
Parameters
database_name- Specifies the name of the database to be created.
<dt><code><em>IF NOT EXISTS</em></code></dt>
<dd>Creates a database with the given name if it doesn't exists. If a database with the same name already exists, nothing will happen.</dd>
<dt><code><em>database_directory</em></code></dt>
<dd>Path of the file system in which the specified database is to be created. If the specified path does not exist in the underlying file system, this command creates a directory with the path. If the location is not specified, the database will be created in the default warehouse directory, whose path is configured by the static configuration spark.sql.warehouse.dir.</dd>
<dt><code><em>database_comment</em></code></dt>
<dd>Specifies the description for the database.</dd>
<dt><code><em>WITH DBPROPERTIES ( property_name=property_value [ , ... ] )</em></code></dt>
<dd>Specifies the properties for the database in key-value pairs.</dd>
Examples
{% highlight sql %}
-- Create database customer_db. This throws exception if database with name customer_db
-- already exists.
CREATE DATABASE customer_db;
-- Create database customer_db only if database with same name doesn't exist.
CREATE DATABASE IF NOT EXISTS customer_db;
-- Create database customer_db only if database with same name doesn't exist with
-- Comments,Specific Location and Database properties.
CREATE DATABASE IF NOT EXISTS customer_db COMMENT 'This is customer database' LOCATION '/user'
WITH DBPROPERTIES (ID=001, Name='John');
-- Verify that properties are set. DESCRIBE DATABASE EXTENDED customer_db; +-------------------------+--------------------------+ |database_description_item|database_description_value| +-------------------------+--------------------------+ | Database Name| customer_db| | Description| This is customer database| | Location| hdfs://hacluster/user| | Properties| ((ID,001), (Name,John))| +-------------------------+--------------------------+ {% endhighlight %}