具体实现方法如下：

exchange.php接口内容如下：

'error','msg'=>'连接超时，请重新打开页面。')); 
    exit; 
} 
$user_id = $_SESSION['zaszh_user_id'];*/  
  
$user_id = 1; // 测试用  
$exchange_points = intval($_GET['exchange_points']);  
  
require('connect_database.php');  
// 扣除答题积分  
$mysqli->query("update zaszh_user set answer_points=answer_points-{$exchange_points} where id='{$user_id}' and answer_points>={$exchange_points}");  
if($mysqli->affected_rows){  
    // 有积分  
    switch($exchange_points){  
        // 5元话费  
        case 200:  
            $mysqli->query("update zaszh_telephone_charge_surplus set charge_surplus=charge_surplus-5 where date=substring(now(),1,10) and charge_surplus>=5");  
            if($mysqli->affected_rows){  
                // 有剩余  
                $mysqli->query("insert into zaszh_award(user_id,prize,create_date) values('{$user_id}','5元话费',unix_timestamp(now()))");  
                if($mysqli->affected_rows){  
                    echo json_encode(array('status'=>'success','msg'=>'5元话费'));  
                }else{  
                    // 获奖失败  
                }  
            }else{  
                // 无剩余  
                // 恢复答题积分  
                $mysqli->query("update zaszh_user set answer_points=answer_points+{$exchange_points} where id='{$user_id}'");  
            }  
            break;  
        // 10元话费  
        case 400:  
            $mysqli->query("update zaszh_telephone_charge_surplus set charge_surplus=charge_surplus-10 where date=substring(now(),1,10) and charge_surplus>=10");  
            if($mysqli->affected_rows){  
                // 有剩余  
                $mysqli->query("insert into zaszh_award(user_id,prize,create_date) values('{$user_id}','10元话费',unix_timestamp(now()))");  
                if($mysqli->affected_rows){  
                    echo json_encode(array('status'=>'success','msg'=>'10元话费'));  
                }else{  
                    // 获奖失败  
                }  
            }else{  
                // 无剩余  
                // 恢复答题积分  
                $mysqli->query("update zaszh_user set answer_points=answer_points+{$exchange_points} where id='{$user_id}'");  
            }  
            break;  
    }  
  
    // 记录积分消耗  
    $mysqli->query("insert into zaszh_answer_points_consume(user_id,points_consume,consume_for,create_date) values('{$user_id}','{$exchange_points}','exchange',unix_timestamp(now()))");  
}else{  
    // 无积分  
    echo json_encode(array('status'=>'error','msg'=>'您的积分不足。'));  
}  
$mysqli->close();