Attempt 2 at more portable key retrieval

GeneratedKeys2.java

public long create(String sql, String[] keyColumns) throws SQLException {
  try (
        Connection connection = dataSource.getConnection();
        PreparedStatement statement = connection.prepareStatement(sql, keyColumns)) {
        
        if (statement.execute() == 0) {
            throw new SQLException("Insert failed, no rows affected.");
        }

        try (ResultSet generatedKeys = statement.getGeneratedKeys()) {
            if (generatedKeys.next()) {
                return generatedKeys.getLong(1);
            } else {
                throw new SQLException("Creating user failed, no ID obtained.");
            }
        }
    }
}