如何使用該列中數值的平均值更新特定列的空單元格？ （使用Java的Mysql）

Question

我想取一列中的所有數值的平均值&用計算平均值更新該列中的空單元格但是在更新空單元格時遇到問題....請給我建議......關注是我的代碼...

/*---------------- Function to apply Mean Imputation Algorithm on saved data in Database -----------------*/ 
public void CalcMean(String tableName) { 

     Statement stmt = null; 
     String sql = null; 
     ResultSet rs = null; 

     try { 

      setConnection(); 
      //connection.setAutoCommit(false); 
      stmt = connection.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE, 
        ResultSet.CONCUR_UPDATABLE); 

      sql = "SELECT * FROM " + tableName; 
      System.out.println("sql :" + sql); 
      rs = stmt.executeQuery(sql); 
      CachedRowSet rowset = new CachedRowSetImpl(); 
      rowset.populate(rs); 

      while(rowset.next()){ 

       ResultSetMetaData rsmd = rowset.getMetaData(); 
       int numOfCols = rsmd.getColumnCount();//get total number of columns from database 

        for(int i = 1; i <= numOfCols; i++){ 
         if (rowset.getString(i)== null || rowset.getString(i).equals("*") || rowset.getString(i).equals("?")) 
         { 
          System.out.println("was NULL"+i);// Database contains NULL 
          String nullCellValue = rowset.getString(i);// get the designated cell's value 
          System.out.println(nullCellValue); 

         } 
         else 
         { 
          System.out.println("not NULL"+i);// Database does not contain NULL 
          String cellValue = rowset.getString(i);// get the designated cell's value 

          System.out.println(cellValue); 

          /*----- check if the value in cell is Numerical or Categorical [0-9]+-----*/ 
          String regex = "[0-9.]+"; 

           if(cellValue.matches(regex)){ 
            System.out.println("Value is numerical"); 

            String colName = rsmd.getColumnName(i); 
            System.out.println(colName); 

            CalcNumericValMean(colName , tableName); 

          } 
          else{ 
           System.out.println("Value is categorical"); 
          } 
         } 
        } 
      } 

      //Clean-up environment 
      rs.close(); 
      stmt.close(); 
      //connection.commit(); 
      closeConnection(); 

     }/*catch (SQLException ex) { 
      try { 
       connection.rollback(); 
       System.out.println("RollBack performed"); 
       closeConnection(); 
       } catch (Exception e1) { 
       System.out.println("RollBack failed"); 
       } 
      } */ 
     catch (Exception e) { 
      // TODO Auto-generated catch block 
      e.printStackTrace(); 
     } 

} 
// Function to Calculate Mean of Numeric Values 
public void CalcNumericValMean(String colName , String tableName){ 

    Statement st = null; 
    String sql = null; 
    String average = null; 

    try{ 

     setConnection(); 
     //connection.setAutoCommit(false); 
     st = connection.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE, 
       ResultSet.CONCUR_UPDATABLE); 

      sql = "SELECT AVG(" + colName + ") FROM " + tableName; 
      System.out.println("sql :" + sql); 

      ResultSet rset = st.executeQuery(sql); 
      CachedRowSet rowset = new CachedRowSetImpl(); 
      rowset.populate(rset); 

      int i = 1; 
      while(rowset.next()) { // check if a result was returned 
        average = rowset.getString(i); // get your result 
        System.out.println("average is : " + average); 
        i++; 
       } 

     //Clean-up environment 
     rset.close(); 
     st.close(); 
     //connection.commit(); 
     closeConnection(); 

    } 
    catch (Exception e) { 
     // TODO Auto-generated catch block 
     e.printStackTrace(); 
    } 

} 

Answer 1

也許你應該試試你的表模型的實現？ 。表模型覆蓋包含public void setValueAt（Object value，int row，int col），您可以在表中的特定列上進行橢圓和數學運算