PHP学习：PHP答题类应用接口实例

<?php 
session_cache_expire(60); 
session_start(); 
if(!isset($_SESSION['zaszh_user_id'])){ 
    echo json_encode(array('status'=>'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 
 
// 随机获取5道问题 
$question_id = array(); 
while(sizeof($question_id)<5){ 
    $num_rand = mt_rand(1,114); 
    if(!in_array($num_rand, $question_id)) 
        $question_id[] = $num_rand; 
} 
 
require('connect_database.php'); 
// 答题次数 
$mysqli->query("update zaszh_user set answer_surplus=answer_surplus-1 where id={$user_id} and answer_surplus>0"); 
if($mysqli->affected_rows){ 
    // 有剩余次数 
}else{ 
    // 无剩余次数 
    echo json_encode(array('status'=>'error','msg'=>'今日答题剩余次数已用完,明天再来哦~')); 
    $mysqli->close(); 
    exit; 
} 
// 题目 
if($stmt = $mysqli->prepare("select question,A,B,C,D,answer from zaszh_question where id in(?,?,?,?,?)")){ 
    $stmt->bind_param('iiiii',$question_id[0],$question_id[1],$question_id[2],$question_id[3],$question_id[4]); 
    $stmt->execute(); 
    $stmt->bind_result($question,$A,$B,$C,$D,$answer); 
    $rows = array(); 
    while($stmt->fetch()){ 
        $rows[] = array( 
            'question'=>$question, 
            'A'=>$A, 
            'B'=>$B, 
            'C'=>$C, 
            'D'=>$D, 
            'answer'=>$answer 
        ); 
    } 
    // 答题记录 
    if($stmt = $mysqli->prepare("insert into zaszh_answer(user_id,question1,question2,question3,question4,question5,create_date) values(?,?,?,?,?,?,unix_timestamp(now()))")){ 
        $stmt->bind_param('iiiiii',$user_id,$question_id[0],$question_id[1],$question_id[2],$question_id[3],$question_id[4]); 
        $stmt->execute(); 
        if($answer_id = $stmt->insert_id){ 
            $param = array( 
                'answer_id'=>$answer_id 
            ); 
            echo json_encode(array_merge($rows,$param)); 
        }else{ 
            echo json_encode(array('status'=>'error','msg'=>'系统出错.')); 
        } 
    } 
    $stmt->close(); 
} 
$mysqli->close();