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>
102 lines
2.9 KiB
Markdown
102 lines
2.9 KiB
Markdown
---
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layout: global
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title: DROP FUNCTION
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displayTitle: DROP FUNCTION
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license: |
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Licensed to the Apache Software Foundation (ASF) under one or more
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contributor license agreements. See the NOTICE file distributed with
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this work for additional information regarding copyright ownership.
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The ASF licenses this file to You under the Apache License, Version 2.0
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(the "License"); you may not use this file except in compliance with
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the License. You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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---
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### Description
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The `DROP FUNCTION` statement drops a temporary or user defined function (UDF). An exception will
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be thrown if the function does not exist.
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### Syntax
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{% highlight sql %}
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DROP [ TEMPORARY ] FUNCTION [ IF EXISTS ] [ db_name. ] function_name
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{% endhighlight %}
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### Parameters
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<dl>
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<dt><code><em>function_name</em></code></dt>
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<dd>The name of an existing function.</dd>
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</dl>
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<dl>
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<dt><code><em>TEMPORARY</em></code></dt>
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<dd>Should be used to delete the `temporary` function.</dd>
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</dl>
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<dl>
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<dt><code><em>IF EXISTS</em></code></dt>
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<dd>If specified, no exception is thrown when the function does not exist.</dd>
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</dl>
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### Example
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{% highlight sql %}
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-- Create a permanent function `test_avg`
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CREATE FUNCTION test_avg as 'org.apache.hadoop.hive.ql.udf.generic.GenericUDAFAverage';
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-- List user functions
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SHOW USER FUNCTIONS;
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+----------------+
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| function|
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+----------------+
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|default.test_avg|
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+----------------+
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-- Create Temporary function `test_avg`
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CREATE TEMPORARY FUNCTION test_avg as 'org.apache.hadoop.hive.ql.udf.generic.GenericUDAFAverage';
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-- List user functions
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SHOW USER FUNCTIONS;
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+----------------+
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| function|
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+----------------+
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|default.test_avg|
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| test_avg|
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+----------------+
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-- Drop Permanent function
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DROP FUNCTION test_avg;
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-- Try to drop Permanent function which is not present
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DROP FUNCTION test_avg;
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Error: Error running query:
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org.apache.spark.sql.catalyst.analysis.NoSuchPermanentFunctionException:
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Function 'default.test_avg' not found in database 'default'; (state=,code=0)
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-- List the functions after dropping, it should list only temporary function
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SHOW USER FUNCTIONS;
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+--------+
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|function|
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+--------+
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|test_avg|
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+--------+
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-- Drop Temporary function
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DROP TEMPORARY FUNCTION IF EXISTS test_avg;
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{% endhighlight %}
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### Related Statements
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* [CREATE FUNCTION](sql-ref-syntax-ddl-create-function.html)
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* [DESCRIBE FUNCTION](sql-ref-syntax-aux-describe-function.html)
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* [SHOW FUNCTION](sql-ref-syntax-aux-show-functions.html)
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