A result was returned by the statement, when none was expected.

Hello all.

I'm using PostgreSQL 7.2.2, with the latest JDBC driver, JDK 1.4.1, under
linux.

In my database, I have several functions defined, and I use them to
insert & update rows in the database. Here is an example.
create function insert_artist (varchar, int) returns bigint as '
insert into artist (name, genre_loid)
values ($1, $2);
select currval(\'loid_seq\');'
language 'sql';
create function update_artist (varchar, bigint, bigint) returns integer as
'
update artist
set name = $1, genre_loid = $2
where loid = $3;
select 1;'
language 'sql';

The insert_artist function returns the last value assigned by a sequence,
and update_artist simply returns the integer 1.

When executed from psql with: select x_artist(...); all is as expected.
When I execute it from Java via:
Statement statement = connection.createStatement();
int result = statement.executeUpdate("select x_artist(...)");
the row is updated or inserted, as is the case, but I get the follwoing
exception.
A result was returned by the statement, when none was expected.
at org.postgresql.jdbc2.Statement.executeUpdate(Statement.java:75)
at com.silverfields.dbAccess.DBObject.save(DBObject.java:205)

What have I done incorrectly? Both functions are defined to return a
single value, and Statement.executeUpdate(String) returns a single value.