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### What changes were proposed in this pull request? SQL Reference cleanup ### Why are the changes needed? To complete SQL Reference ### Does this PR introduce _any_ user-facing change? updated sql-ref-syntax-qry.html before <img width="1100" alt="Screen Shot 2020-04-29 at 11 08 25 PM" src="https://user-images.githubusercontent.com/13592258/80677799-70b27280-8a6e-11ea-8e3f-a768f29d0377.png"> after <img width="1100" alt="Screen Shot 2020-04-29 at 11 05 55 PM" src="https://user-images.githubusercontent.com/13592258/80677803-74de9000-8a6e-11ea-880c-aa05c53254a6.png"> ### How was this patch tested? Manually build and check Closes #28417 from huaxingao/cleanup. Authored-by: Huaxin Gao <huaxing@us.ibm.com> Signed-off-by: Takeshi Yamamuro <yamamuro@apache.org>
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| layout | title | displayTitle | license |
|---|---|---|---|
| global | DROP FUNCTION | DROP FUNCTION | 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 DROP FUNCTION statement drops a temporary or user defined function (UDF). An exception will
be thrown if the function does not exist.
Syntax
{% highlight sql %} DROP [ TEMPORARY ] FUNCTION [ IF EXISTS ] function_name {% endhighlight %}
Parameters
function_name-
Specifies the name of an existing function. The function name may be
optionally qualified with a database name.
Syntax:[ database_name. ] function_name
TEMPORARY- Should be used to delete the
TEMPORARYfunction.
IF EXISTS- If specified, no exception is thrown when the function does not exist.
Examples
{% highlight sql %}
-- Create a permanent function test_avg
CREATE FUNCTION test_avg as 'org.apache.hadoop.hive.ql.udf.generic.GenericUDAFAverage';
-- List user functions SHOW USER FUNCTIONS; +----------------+ | function| +----------------+ |default.test_avg| +----------------+
-- Create Temporary function test_avg
CREATE TEMPORARY FUNCTION test_avg AS
'org.apache.hadoop.hive.ql.udf.generic.GenericUDAFAverage';
-- List user functions SHOW USER FUNCTIONS; +----------------+ | function| +----------------+ |default.test_avg| | test_avg| +----------------+
-- Drop Permanent function DROP FUNCTION test_avg;
-- Try to drop Permanent function which is not present DROP FUNCTION test_avg; Error: Error running query: org.apache.spark.sql.catalyst.analysis.NoSuchPermanentFunctionException: Function 'default.test_avg' not found in database 'default'; (state=,code=0)
-- List the functions after dropping, it should list only temporary function SHOW USER FUNCTIONS; +--------+ |function| +--------+ |test_avg| +--------+
-- Drop Temporary function DROP TEMPORARY FUNCTION IF EXISTS test_avg; {% endhighlight %}