주식 각 종목의 가장 최근 결과 가져오기

                SELECT DISTINCT ON (i.code) 
                       i.code, i.date, i.last_actual_price, i.final_predicted_price,
                       i.price_change, i.price_change_percent, i.test_r2, i.volatility, 
                       i.prediction_days, i.last_actual_date,
                       i.train_r2, i.test_mse, i.test_rmse, i.test_mae,
                       c.name as company_name, c.rank, i.model_info
                FROM investment i
                JOIN company c ON i.code = c.code
                ORDER BY i.code, i.date DESC