check the execution status of stored procedure

Currently, I try to call a stored procedure with void returned type.

PGresult *res = PQexec(this->getConnection(), "SELECT * FROM create_tables()");
if (PQresultStatus(res) != PGRES_COMMAND_OK)
{
PQclear(res);
return false;
}

Since the returned type of stored procedure is void, I will always fall in to the block

if (PQresultStatus(res) != PGRES_COMMAND_OK) {}

Is there any better way, I can check whether the stored procedure had been executed without problem?

Thanks and Regards
Yan Cheng CHEOK