String sql="select * from t_dept where id = ? and name = ?";
        PreparedStatement ps=conn.prepareStatement(sql);
        ps.setInt(1,id);
        ps.setString(2,name);
        System.out.println(ps);
        ResultSet resultSet = ps.executeQuery();
        while(resultSet.next()){
            flag++;
//　　　　　　　//对应的类是自己数据对应的
            User user = new User();
            user.setId(resultSet.getInt(1));
            user.setName(resultSet.getString(2));
            System.out.println(user);