java - 如何从数据库中检索一列数据的总和？

如何从数据库中检索一列数据的总和并从数据库中的另一列数据中求和？我想这样做，从Total_Sales列中获取总和，从Total_Value列中获取总和，然后执行subract操作，即从Total_Sales的值（Total_Sales-Total_Value）中求和。目前，这是我的代码。

calculateButton.addActionListener(new ActionListener()
    {
    public void actionPerformed(ActionEvent ae)
    {

    try
    {
        Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
        Connection conn = DriverManager.getConnection("Jdbc:Odbc:TomsJava");

        java.util.Date fromDate=(java.util.Date)fromtextField.getValue();
        java.util.Date toDate=(java.util.Date)totextField.getValue();

        PreparedStatement ps = conn.prepareStatement("select SUM(Total_Sales - Total_Value) As Result from DailyAnalysis where 'Date1 BETWEEN #fromDate# AND #toDate#' ");
        ResultSet rs = ps.executeQuery();
        while(rs.next())
        {

            String itemName = rs.getString("Item");
            Double totalValue = rs.getDouble("Total_Value");
            Double totalSales = rs.getDouble("Total_Sales");

            Double Result = rs.getDouble(1);

        }

    }
    catch(SQLException s)
    {
        System.out.println(s);
    }
    catch(ClassNotFoundException z)
    {
        System.out.println(z);
    }
    catch(NumberFormatException n)
    {
        System.out.println(n);
    }
    }
    });

编辑
我正在尝试检索两个日期之间的列。我想将Total_Value的检索值的总和设置为Total Expense文本字段，并将Total_Sales列的总和设置为Total Income文本字段。然后据此计算损益。

最佳答案

Select Sum(Total_Sales) as Sales_Total, Sum(Total_Value) as Value_Total, Sum(Total_Sales - Total_Value) as Result
From DailyAnalysis

将查询和代码更改为此

     Double result = null;
     Double totalValue = null;
     Double totalSales = null;
      ...

      PreparedStatement ps = conn.prepareStatement("select Sum(Total_Sales) as Sales_Total, Sum(Total_Value) as Value_Total, SUM(Total_Sales - Total_Value) As Result from DailyAnalysis where Date1 BETWEEN ? AND ? ");
            ps.setDate(1,fromDate)
            ps.setDate(2,toDate)
            ResultSet rs = ps.executeQuery();

            //Query should only return one or zero result hence the if statement
            if (rs.next())
            {
               //Define variables at the top, if you want to have access outside the if block scope
               totalValue = rs.getDouble("Value_Total");
               totalSales = rs.getDouble("Sales_Total");
               result = rs.getDouble("Result");
            }