---
layout: global
title: DROP FUNCTION
displayTitle: DROP FUNCTION 
license: |
  Licensed to the Apache Software Foundation (ASF) under one or more
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  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
 
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---

### 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

```sql
DROP [ TEMPORARY ] FUNCTION [ IF EXISTS ] function_name
```

### 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 `TEMPORARY` function.

* **IF EXISTS**

    If specified, no exception is thrown when the function does not exist.

### Examples

```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;
```

### Related Statements

* [CREATE FUNCTION](sql-ref-syntax-ddl-create-function.html)
* [DESCRIBE FUNCTION](sql-ref-syntax-aux-describe-function.html)
* [SHOW FUNCTION](sql-ref-syntax-aux-show-functions.html)