> ## Documentation Index
> Fetch the complete documentation index at: https://cockroachlabs.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.
# CREATE FUNCTION
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return
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The `CREATE FUNCTION` statement creates a user-defined function.
The \`\` statement performs a schema change. For more information about how online schema changes work in CockroachDB, see Online Schema Changes.
## Required privileges
* To define a function, a user must have `CREATE` privilege on the schema of the function.
* To define a function with a user-defined type, a user must have `USAGE` privilege on the user-defined type.
* To resolve a function, a user must have at least the `USAGE` privilege on the schema of the function.
* To call a function, a user must have `EXECUTE` privilege on the function.
* At function definition and execution time, a user must have privileges on all the objects referenced in the function body. Privileges on referenced objects can be revoked and later function calls can fail due to lack of permission.
If you grant `EXECUTE` privilege as a default privilege at the database level, newly created functions inherit that privilege from the database.
## Synopsis
## Parameters
| Parameter | Description |
| ------------------ | --------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `func_create_name` | The name of the function. |
| `func_param` | A function argument. |
| `func_return_type` | The type returned by the function. |
| `opt_routine_body` | The body of the function. For allowed contents, see User-Defined Functions: Overview. |
## Example of a simple function
The following statement creates a function to compute the square of integers:
```sql theme={"theme":{"light":"catppuccin-mocha","dark":"catppuccin-mocha"}}
CREATE OR REPLACE FUNCTION sq(a INT) RETURNS INT AS 'SELECT a*a' LANGUAGE SQL;
```
The following statement invokes the `sq` function:
```sql theme={"theme":{"light":"catppuccin-mocha","dark":"catppuccin-mocha"}}
SELECT sq(2);
```
```
sq
-----
4
(1 row)
```
## Examples of functions that reference tables
#### Setup
The following examples use MovR, a fictional vehicle-sharing application, to demonstrate CockroachDB SQL statements. For more information about the MovR example application and dataset, see MovR: A Global Vehicle-sharing App.
To follow along, run `cockroach demo` to start a temporary, in-memory cluster with the `movr` dataset preloaded:
```shell theme={"theme":{"light":"catppuccin-mocha","dark":"catppuccin-mocha"}}
$ cockroach demo
```
### Create a function that references a table
The following statement defines a function that returns the total number of MovR application users.
```sql theme={"theme":{"light":"catppuccin-mocha","dark":"catppuccin-mocha"}}
CREATE OR REPLACE FUNCTION num_users() RETURNS INT AS 'SELECT count(*) FROM users' LANGUAGE SQL;
```
```sql theme={"theme":{"light":"catppuccin-mocha","dark":"catppuccin-mocha"}}
SELECT num_users();
```
```
num_users
-------------
50
(1 row)
```
### Create a function that uses a `WHERE` clause
The following statement defines a function that returns the total revenue for rides taken in European cities.
```sql theme={"theme":{"light":"catppuccin-mocha","dark":"catppuccin-mocha"}}
CREATE OR REPLACE FUNCTION total_euro_revenue() RETURNS DECIMAL LANGUAGE SQL AS $$
SELECT SUM(revenue) FROM rides WHERE city IN ('paris', 'rome', 'amsterdam')
$$;
```
```sql theme={"theme":{"light":"catppuccin-mocha","dark":"catppuccin-mocha"}}
SELECT total_euro_revenue();
```
```
total_euro_revenue
----------------------
8468.00
```
### Create a function that returns a set of results
The following statement defines a function that returns information for all vehicles not in use. The `SETOF` clause specifies that the function should return each row as the query executes to completion.
```sql theme={"theme":{"light":"catppuccin-mocha","dark":"catppuccin-mocha"}}
CREATE OR REPLACE FUNCTION available_vehicles() RETURNS SETOF vehicles LANGUAGE SQL AS $$
SELECT * FROM vehicles WHERE status = 'available'
$$;
```
```sql theme={"theme":{"light":"catppuccin-mocha","dark":"catppuccin-mocha"}}
SELECT city,current_location,type FROM available_vehicles();
```
```
city | current_location | type
----------------+-----------------------------+-------------
amsterdam | 4102 Stout Flat Apt. 11 | skateboard
boston | 30226 Logan Branch Suite 76 | skateboard
los angeles | 25730 Crystal Terrace | scooter
paris | 9429 Joseph Neck Suite 52 | skateboard
san francisco | 43325 Jeffrey Wall Suite 26 | scooter
(5 rows)
```
### Create a function that returns a `RECORD` type
The following statement defines a function that returns the information for the user that most recently completed a ride. The information is returned as a record, which takes the structure of the row that is retrieved by the selection query.
In the function subquery, the latest `end_time` timestamp is used to determine the most recently completed ride.
```sql theme={"theme":{"light":"catppuccin-mocha","dark":"catppuccin-mocha"}}
CREATE OR REPLACE FUNCTION last_rider() RETURNS RECORD LANGUAGE SQL AS $$
SELECT * FROM users WHERE id = (
SELECT rider_id FROM rides WHERE end_time = (SELECT max(end_time) FROM rides)
)
$$;
```
```sql theme={"theme":{"light":"catppuccin-mocha","dark":"catppuccin-mocha"}}
SELECT last_rider();
```
```
last_rider
----------------------------------------------------------------------------------------------------------
(70a3d70a-3d70-4400-8000-000000000016,seattle,"Mary Thomas","43322 Anthony Flats Suite 85",1141093639)
(1 row)
```
## See also
* User-Defined Functions
* `ALTER FUNCTION`
* `DROP FUNCTION`
* SQL Statements
* Online Schema Changes