java - sql查询在eclipse中不起作用

我有一个查询在SQLyog中运行得很好，但在eclipse中没有。调试时显示的错误是“找不到列”。
我的问题是：

String searchQuery = "select AVG(Rating) from rating where CoursesID=? and MONTH(dtDate)=? group by dtDate";

表格：

ID     | CoursesID | Rating | Comment | dtDate

11111  | SKM3207   | 5      | No      | 2015-05-20

爪哇

//preparing some objects for connection
       Connection currentCon = null;
       ResultSet rs = null;
       PreparedStatement pstmt = null;
       //double totalRate = 0.0;

       Vector<String> monthRating = new Vector<String>();

       try{
           String searchQuery = "select AVG(Rating) from rating where CoursesID=? and MONTH(dtDate)=? group by dtDate";

           //connect to DB
           currentCon = ConnectionManager.getConnection();
           pstmt=currentCon.prepareStatement(searchQuery);
           pstmt.setString(1, CoursesID);
           pstmt.setString(2, fmonth);
           rs = pstmt.executeQuery();

           while(rs.next()){
               monthRating.add(rs.getString("Rating"));
               //String avg = rs.getString(1);
               //totalRate = Double.parseDouble(avg);
           }
        }

        catch (Exception ex){
           System.out.println("Log In failed: An Exception has occurred! " + ex);
        }

        //some exception handling
        finally{
           if (rs != null)  {
              try {
                 rs.close();
              } catch (Exception e) {}
                 rs = null;
              }

           if (pstmt != null) {
              try {
                pstmt.close();
              } catch (Exception e) {}
                pstmt = null;
              }

           if (currentCon != null) {
              try {
                 currentCon.close();
              } catch (Exception e) {
              }

                currentCon = null;
           }
        }

          return monthRating;

是否需要在其中添加任何内容，以便在eclipse中运行它？

最佳答案

您正在使用Rating asrs.getString("Rating")，而Rating在聚合中使用时在sql语句中没有别名。只需添加别名

SELECT AVG(Rating) AS Rating ....

关于java - sql查询在eclipse中不起作用，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/30497004/