---
layout: default_docs
title: Chapter 6. Calling Stored Functions
header: Chapter 6. Calling Stored Functions
resource: media
previoustitle: Creating and Modifying Database Objects
previous: ddl.html
nexttitle: Chapter 7. Storing Binary Data
next: binary-data.html
---
**Table of Contents**
* [Obtaining a `ResultSet` from a stored function](callproc.html#callproc-resultset)
* [From a Function Returning `SETOF` type](callproc.html#callproc-resultset-setof)
* [From a Function Returning a refcursor](callproc.html#callproc-resultset-refcursor)
**Example 6.1. Calling a built in stored function**
This example shows how to call a PostgreSQL™ built in function, `upper`, which
simply converts the supplied string argument to uppercase.
`CallableStatement upperProc = conn.prepareCall("{ ? = call upper( ? ) }");`
`upperProc.registerOutParameter(1, Types.VARCHAR);`
`upperProc.setString(2, "lowercase to uppercase");`
`upperProc.execute();`
`String upperCased = upperProc.getString(1);`
`upperProc.close();`
# Obtaining a `ResultSet` from a stored function
PostgreSQL's™ stored functions can return results in two different ways. The
function may return either a refcursor value or a `SETOF` some datatype. Depending
on which of these return methods are used determines how the function should be
called.
## From a Function Returning `SETOF` type
Functions that return data as a set should not be called via the `CallableStatement`
interface, but instead should use the normal `Statement` or `PreparedStatement`
interfaces.
**Example 6.2. Getting `SETOF` type values from a function**
`Statement stmt = conn.createStatement();`
`stmt.execute("CREATE OR REPLACE FUNCTION setoffunc() RETURNS SETOF int AS "`
`+ "' SELECT 1 UNION SELECT 2;' LANGUAGE sql");`
`ResultSet rs = stmt.executeQuery("SELECT * FROM setoffunc()");`
`while (rs.next())`
`{`
`// do something`
`}`
`rs.close();`
`stmt.close();`
## From a Function Returning a refcursor
When calling a function that returns a refcursor you must cast the return type of
`getObject` to a `ResultSet`
### Note
> One notable limitation of the current support for a `ResultSet` created from
a refcursor is that even though it is a cursor backed `ResultSet`, all data will
be retrieved and cached on the client. The `Statement` fetch size parameter
described in the section called [“Getting results based on a cursor”](query.html#query-with-cursor)
is ignored. This limitation is a deficiency of the JDBC driver, not the server,
and it is technically possible to remove it, we just haven't found the time.
**Example 6.3. Getting refcursor Value From a Function**
`// Setup function to call.`
`Statement stmt = conn.createStatement();`
`stmt.execute("CREATE OR REPLACE FUNCTION refcursorfunc() RETURNS refcursor AS '"`
`+ " DECLARE "`
`+ " mycurs refcursor; "`
`+ " BEGIN "`
`+ " OPEN mycurs FOR SELECT 1 UNION SELECT 2; "`
`+ " RETURN mycurs; "`
`+ " END;' language plpgsql");`
`stmt.close();`
`// We must be inside a transaction for cursors to work.`
`conn.setAutoCommit(false);`
`// Procedure call.`
`CallableStatement proc = conn.prepareCall("{ ? = call refcursorfunc() }");`
`proc.registerOutParameter(1, Types.OTHER);`
`proc.execute();`
`ResultSet results = (ResultSet) proc.getObject(1);`
`while (results.next())`
`{`
`// do something with the results.`
`}`
`results.close();`
`proc.close();`
It is also possible to treat the refcursor return value as a cursor name directly.
To do this, use the `getString` of `ResultSet`. With the underlying cursor name,
you are free to directly use cursor commands on it, such as `FETCH` and `MOVE`.
**Example 6.4. Treating refcursor as a cursor name**
`conn.setAutoCommit(false);`
`CallableStatement proc = conn.prepareCall("{ ? = call refcursorfunc() }");`
`proc.registerOutParameter(1, Types.OTHER);`
`proc.execute();`
`String cursorName = proc.getString(1);`
`proc.close();`