如何使用该列中的平均值来更新特定列的空单元格？ （使用java的Mysql）

Question

我想取一列中的所有数值的平均值。使用计算的平均值更新该列中的空单元格但是在更新空单元格期间面临问题....请给我建议......以下是我的代码...

/*---------------- 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

也许您应该尝试使用表模型实现？ 。表模型覆盖包含public void setValueAt（Object value，int row，int col），您可以在表格的特定列上进行数学处理