的JFreeChart使用数字查询Oracle错误

Question

我试图做一个查询这样的主题：JFreeChart using numeric query ORACLE

生成一个条形图，可是我总接收错误：值java.sql.SQLException：JDBCCategoryDataset.executeQuery（ ）：从数据库返回的列不足。

我的代码如下：

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 

什么，我做错了什么？

Answer 1

上面引用的SQL会导致错误（使用SQL Fiddle来检查代码），因为两个case语句不匹配JFreeChart只是重新使用误导性消息来抛出错误。

如果你的SQL是正确的JFreeChart告诉你，你需要结果集中有额外的列，因为你将case语句与查询总数连接起来，如果它工作的话，只会返回一列。

尝试使用这个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)