的JFreeChart使用數字查詢Oracle錯誤

Question

我試圖做一個查詢這樣的主題：JFreeChart using numeric query ORACLE

生成一個條形圖，可是我總接收錯誤：值java.sql.SQLException：JDBCCategoryDataset.executeQuery（ ）：從數據庫返回的列不足。

我的代碼如下：

SELECT CASE WHEN TIME>23.73 AND TIME<=24.0 THEN '23.73<TIME<=24.10' 
    WHEN TIME>24.10 AND TIME<=25.68 THEN '24.10<TIME<=25.68'   
    WHEN TIME>25.68 AND TIME<=27.36 THEN '25.68<TIME<=27.36' 
     ELSE '27.36<TIME' 
    END || ' with value '|| COUNT(*) v FROM SWIMMER 
GROUP BY CASE 
WHEN TIME>23.73 AND TIME<=24.10 THEN '23.73<TIME<=24.10' 
WHEN TIME>24.10 AND TIME<=25.68 THEN '24.10<TIME<=25.68' 
WHEN TIME>25.68 AND TIME<=27.36 THEN '25.68<TIME<=27.36' 
ELSE '27.36<TIME' END 

什麼，我做錯了什麼？

Answer 1

上面引用的SQL會導致錯誤（使用SQL Fiddle來檢查代碼），因爲兩個case語句不匹配JFreeChart只是重新使用誤導性消息來拋出錯誤。

如果你的SQL是正確的JFreeChart告訴你，你需要結果集中有額外的列，因爲你將case語句與查詢總數連接起來，如果它工作的話，只會返回一列。

嘗試使用這個SQL：

SELECT time_range || ' with value ' || total as category, total 
    FROM (SELECT time_range, COUNT(*) AS total 
      FROM (SELECT CASE 
         WHEN TIME > 23.73 
           AND TIME <= 24.0 THEN 
          '23.73<TIME<=24.10' 
         WHEN TIME > 24.10 
           AND TIME <= 25.68 THEN 
          '24.10<TIME<=25.68' 
         WHEN TIME > 25.68 
           AND TIME <= 27.36 THEN 
          '25.68<TIME<=27.36' 
         ELSE 
          '27.36<TIME' 
         END AS time_range 
        FROM swimmer) 
     GROUP BY time_range)